opinion: Me. Justice Stewart
  delivered the opinion of the Court.
  The petitioner was convicted for having unlawfully refused to answer a question pertinent to a matter under inquiry before a subcommittee of the House Committee on Un-American Activities at a hearing in Atlanta, Georgia, on July 30, 1958. His conviction was affirmed by the Court of Appeals, which held that our decision in Barenblatt v. United States, 360 U. S. 109, was “controlling.” 272 F. 2d 783. We granted certiorari, 362 U. S. 926, to consider the petitioner’s claim that the Court of Appeals had misconceived the meaning of the Baren-blatt decision. For the reasons that follow, we are of the view that the Court of Appeals was correct, and that its judgment must be affirmed.
  I.
  The following circumstances were established by uncon-troverted evidence at the petitioner’s trial:
  The Committee on Un-American Activities is a standing committee of the House of Representatives, elected at the commencement of each Congress. The Committee, or any subcommittee thereof, is authorized to investigate “(i) the extent, character, and objects of un-American propaganda activities in the United States, (ii) the diffusion within the United States of subversive and un-American propaganda that is instigated from foreign countries or of a domestic origin and attacks the principle of the form of government as guaranteed by our Constitution, and (iii) all other questions in relation thereto that would aid Congress in any necessary remedial legislation.”
  In the spring of 1958 the Committee passed a resolution providing for a subcommittee hearing to be held in Atlanta, Georgia, "relating to the following subjects and having the legislative purposes indicated:
  “1. The extent, character and objects of Communist colonization and infiltration in the textile and other basic industries located in the South, and Communist Party propaganda activities in the South, the legislative purpose being:
  “(a) To obtain additional information for use by the Committee in its consideration of Section 16 of H. R. 9352, relating to the proposed amendment of Section 4 of the Communist Control Act of 1954, prescribing a penalty for knowingly and wilfully becoming or remaining a member of the Communist Party with knowledge of the purposes or objectives thereof; and
  “(b) To obtain additional information, adding to the Committee’s overall knowledge on the subject so that Congress may be kept informed and thus prepared to enact remedial legislation in the National Defense, and for internal security, when and if the exigencies of the situation require it.
  “2. Entry and dissemination within the United States of foreign Communist Party propaganda, the legislative purpose being to determine the necessity for, and advisability of, amendments to the Foreign Agents Registration Act designed more effectively to counteract the Communist schemes and devices now used in avoiding the prohibitions of the Act.
  “3. Any other matter within the jurisdiction of the Committee which it, or any subcommittee thereof, appointed to-conduct this hearing, may designate.”
  The subcommittee which was appointed pursuant to this resolution convened in Atlanta on July 29, 1958. At the opening of the proceedings on that day, the Chairman of the Committee orally summarized the purposes of the hearings. The petitioner was present and heard the Chairman’s statement.
  The first witness to appear was Amando Penha, who testified that he had been a member of the Communist Party from 1950 to 1958, having joined the Party at the request of the Federal Bureau of Investigation. He stated that he had served as a member of the National Textile Commission of the Party, which, he said, was set up to control and supervise the infiltration and colonization of the textile industry, particularly in the South. He described the “colonizer” system, which, he said, involves sending hard-core Party members into plants in jobs where they have close contact with rank-and-file workers. Penha described in some detail his trips throughout the South in compliance with the instructions of the National Textile Commission, and identified a number of individuals as “colonizers.” Another witness, a Deputy Collector of Customs, described the influx of Communist propaganda sent from abroad into the United States and particularly into the South. Several other witnesses were then interrogated, some as to their activities as alleged Communist colonizers, others as to their connection with certain allegedly Communist-controlled publications. A number of these witnesses declined to answer most of the questions put to them.
  On the following day the first witness before the subcommittee was Carl Braden. Although interrogated at length he declined to answer questions relating to alleged Communist activity. The next witness was the petitioner. After being sworn and stating his name he declined to give his residence address, stating that, “As a matter of conscience and personal responsibility, I refuse to answer any questions of this committee.” When asked his occupation, he made the same response. He was then asked the question which was to become the subject of the present indictment and conviction: “Mr. Wilkinson, are you now a member of the Communist Party?” He declined to answer the question, giving the same response as before.
  The Committee’s Staff Director then addressed the petitioner at length, in explanation “of the reasons, the perti-nency, and the relevancy of that question and certain other questions which I propose to propound to you.”
  In response the petitioner stated “I am refusing to answer any questions of this committee.” He was then directed by the Subcommittee Chairman to answer the question as to his Communist Party membership. This time he responded as follows:
  “I challenge, in the most fundamental sense, the legality of the House Committee on Un-American Activities. It is my opinion that this committee stands in direct violation by its mandate and by its practices of the first amendment to the United States Constitution. It is my belief that Congress had no authority to establish this committee in the first instance, nor to instruct it with the mandate which it has.
  “I have the utmost respect for the broad powers which the Congress of the United States must have to carry on its investigations for legislative purposes. However, the United States Supreme Court has held that, broad as these powers may be, the Congress cannot investigate into an area where it cannot legislate, and this committee tends, by its mandate and by its practices, to investigate into precisely those areas of free speech, religion, peaceful association and' assembly, and the press, wherein it cannot legislate and therefore it cannot investigate.”
  The hearing continued. The Staff Director read part of the record of an earlier hearing in California, where a witness had testified to knowing the petitioner as a Communist. The petitioner was then asked whether this testimony was true. He refused to answer this and several further questions addressed to him. There was introduced into the record a reproduction of the petitioner’s registration at an Atlanta hotel a week earlier, in which he had indicated that his business firm association was the “Emergency Civil Liberties Committee.”
  The subsequent indictment and conviction of the petitioner were based upon his refusal, in the foregoing context, to answer the single question “Are you now a member of the Communist Party?”
  II.
  The judgment affirming the petitioner's conviction is attacked here from several different directions. It is contended that the subcommittee was without authority to interrogate him, because its purpose in doing so was to investigate public opposition to the Committee itself and to harass and expose him. It is argued that the petitioner was wrongly convicted because the question which he refused to answer was not pertinent to a question under inquiry by the subcommittee, so that a basic element of the statutory offense was lacking. It is said that in any event the pertinency of the question was not made clear to the petitioner at the time he was directed to answer it, so that he was denied due process. Finally, it is urged that the action of the subcommittee in subpoenaing and questioning him violated his rights under the First Amendment to the Constitution.
  In considering these contentions the starting point must be to determine the subject matter of the subcommittee’s inquiry. House Rule XI, which confers investigative authority upon the Committee and its subcommittees, is quoted above. Because of the breadth and generality of its language, Rule XI cannot be said to state with adequate precision the subject under inquiry by a subcommittee at any given hearing. This the Court had occasion to point out in Watkins v. United States, 354 U. S. 178. See also Barenblatt v. United States, 360 U. S. 109, 116-117. But, as the Watkins opinion recognized, Rule XI is only one of several possible points of reference. The Court in that case said that “[t]he authorizing resolution, the remarks of the chairman or members of the committee, or even the nature of the proceedings themselves” might reveal the subject under inquiry. 354 U. S., at 209. Here, as in Barenblatt, other sources do supply the requisite concreteness.
  . The resolution authorizing the subcommittee hearing in Atlanta was explicit. It clearly set forth three concrete areas of investigation: Communist infiltration into basic industry in the South, Communist Party- propaganda in the South, and foreign Communist Party propaganda in the United States. The pattern of interrogation of the witnesses who appeared on the first day of the hearing confirms that the subcommittee was pursuing those three subjects of investigation. The Staff Director’s statement to the petitioner explicitly referred to the second of the three subjects — Communist Party propaganda in the South. We think that the record thus clearly establishes that the subcommittee at the time of the petitioner’s interrogation was pursuing at least two related and specific subjects of investigation: Communist infiltration into basic southern industry, and Communist Party propaganda activities in that area of the country.
  If these, then, were the two subjects of the subcommittee’s inquiry, the questions that must be answered in considering the petitioner’s contentions are several. First, was the subcommittee’s investigation of these subjects, through interrogation of the petitioner, authorized by Congress? Second, was the subcommittee pursuing a valid legislative purpose? Third, was the question asked the petitioner pertinent to the subject matter of the investigation? Fourth, was he contemporaneously apprised of the pertinency of the question? Fifth, did the subcommittee’s interrogation violate his First Amendment rights of free association and free speech?
  The question of basic congressional authorization was clearly decided in Barenblatt v. United States, supra. There we said, after reviewing the genesis and subsequent history of Rule XI, that “[I]t can hardly be seriously argued that the investigation of Communist activities generally, and the attendant use of compulsory process, was beyond the purview of the Committee’s intended authority under Rule XI.” 360 U. S., at 120-121. The subjects under inquiry here surely fall within “the investigation'of Communist activities generally.”
  The petitioner argues, however, that the subcommittee was inspired to interrogate him by reason of his opposition to the existence of the Un-American Activities Committee itself, and that its purpose was unauthorized harassment and exposure. He points to the Chairman’s opening statement which mentioned activity against the Committee, to the fact that he was subpoenaed to appear before the subcommittee soon after he arrived in Atlanta to stir up opposition to the Committee’s activities, and to the statement of the Staff Director indicating the subcommittee’s awareness of his efforts to develop a “hostile sentiment” to the Committee and to “bring pressure upon the United States Congress to preclude these particular hearings.”
  But, just as in Barenblatt, supra, we could find nothing in Rule XI to exclude the field of education from the Committee’s compulsory authority, we can find nothing to indicate that it was the intent of Congress to immunize from interrogation all those (and there are many) who are opposed to the existence of the Un-American Activities Committee.
  Nor can we say on this record that the subcommittee was not pursuing a valid legislative purpose. The Committee resolution authorizing the Atlanta hearing, quoted above, expressly referred to two legislative proposals, an amendment to § 4 of the Communist Control Act of 1954 and amendments to the Foreign Agents Registration Act of 1938. A number of other sources also indicate the presence of a legislative purpose. The Chairman’s statement at the opening of the hearings contained a lengthy discussion of legislation. The Staff Director’s statement to the petitioner also discussed legislation which the Committee had under consideration. All these sources indicate the existence of a legislative purpose. And the determination that purposes of the kind referred to are unassailably valid was a cornerstone of our decision in Barenblatt, supra: “That Congress has wide power to legislate in the field of Communist activity in this Country, and to conduct appropriate investigations in aid thereof, is hardly debatable. The existence of such power has never been questioned by this Court, and it is sufficient to say, without particularization, that Congress has enacted or considered in this field a wide range of legislative measures, not a few of which have stemmed from recommendations of the very Committee whose actions have been drawn in question here. In the last analysis this power rests on the right of self-preservation. . . 360 U. S., at 127-128.
  The petitioner’s contention. that, while the hearing generally may have been pursuant to a valid legislative purpose, the sole reason for interrogating him was to expose him to public censure because of his activities against the Committee is not persuasive. It is true that the Staff Director’s statement reveals the subcommittee’s awareness of the petitioner’s opposition to the hearings and indicates that the petitioner was not summoned to appear until after he had arrived in Atlanta as the representative of a group carrying on a public campaign to abolish the House Committee. These circumstances, however, do not necessarily lead to the conclusion that the subcommittee’s intent was personal persecution of the petitioner. As we have noted, a prime purpose of the hearings was to investigate Communist propaganda activities in the South. It therefore was entirely logical for the subcommittee to subpoena the petitioner after he had arrived at the site of the hearings, had registered as a member of a group which the subcommittee believed to be Communist dominated, and had conducted a public campaign against the subcommittee. The fact that the petitioner might not have been summoned to appear had he not come to Atlanta illustrates the very point, for in that event he might not have been thought to have been connected with a subject under inquiry — Communist Party propaganda activities in that area of the country.
  Moreover, it is not for us to speculate as to the motivations that may have prompted the decision of individual members of the subcommittee to summon the petitioner. As was said in Watkins, supra, “a solution to our problem is not to be found in testing the motives of committee members for this purpose. Such is not our function. Their motives alone would not vitiate an investigation which had been instituted by a House of Congress if that assembly’s legislative purpose is being served.” 354 U. S., at 200. See also Barenblatt, supra, 360 U. S., at 132.
  It is to be emphasized that the petitioner was not summoned to appear as the result of an indiscriminate dragnet procedure, lacking in probable cause for belief that he possessed information which might be helpful to the subcommittee. As was made clear by the testimony of the Committee’s Staff Director at the trial, the subcommittee had reason to believe at the time it summoned the petitioner that he was an active Communist leader engaged primarily in propaganda activities. This is borne out by. the record of the subcommittee hearings, including the content of the Staff Director’s statement to the petitioner and evidence that at a prior hearing the petitioner had been identified as a Communist Party member.
  The petitioner’s claim that the question he refused to answer was not pertinent to a subject under inquiry merits no extended discussion. Indeed, it is difficult to imagine a preliminary question more pertinent to the topics under investigation than whether petitioner was in fact a member of the Communist Party. As was said in Barenblatt, “petitioner refused to answer questions as to his own Communist Party affiliations, whose per-tinency of course was clear beyond doubt.” 360 U. S., at 125. The contention that the pertinency of the question was not made clear to the petitioner at the time he was directed to answer it is equally without foundation. After the Staff Director gave a detailed explanation of the question’s pertinency, the petitioner said nothing to indicate that he entertained any doubt on this score.
  We come finally to the claim that the subcommittee’s interrogation of the petitioner violated his rights under the First Amendment. The basic issues which this contention raises were thoroughly canvassed by us in Baren- blatt. Substantially all that was said there is equally applicable here, and it would serve no purpose to enlarge this opinion with a paraphrased repetition of what was in that opinion thoughtfully considered and carefully expressed. See 360 U. S., at 125-134.
  It is sought to differentiate this case upon the basis that “the activities in which petitioner was believed to be participating consisted of public criticism of the Committee and attempts to influence public opinion to petition Congress for redress — to abolish the Committee.” But we cannot say that, simply because the petitioner at the moment may have been engaged in lawful conduct, his Communist activities in connection therewith could not be investigated. The subcommittee had reasonable ground to suppose that the petitioner was an active Communist Party member, and that as such he possessed information that would substantially aid it in its legislative investigation. As the Barenblatt opinion makes clear, it is the nature of the Communist activity involved,' whether the momentary conduct is legitimate or illegitimate politically, that establishes the Government’s overbalancing interest. “To suggest that because the Communist Party may also sponsor peaceable political reforms the constitutional issues before us should now be judged as if that Party were just an ordinary political party from the standpoint of national security, is to ask this Court to blind itself to world affairs which have determined the whole course of our national policy since the close of World War II. . . .” 360 U. S., at 128-129.
  The subcommittee’s legitimate legislative interest was not the activity in which the petitioner might have happened at the time to be engaged, but in the manipulation and infiltration of activities and organizations by’persons advocating overthrow of the Government. “The strict requirements of a prosecution under the Smith Act . . . are not the measure of the permissible scope of a congressional investigation into ‘overthrow/ for of necessity the investigatory process must proceed step by step.” 360 U. S., at 130.
  We conclude that the First Amendment claims pressed here are indistinguishable from those considered in Barenblatt, and that upon the reasoning and the authority of that case they cannot prevail.
  Affirmed.
  The applicable statute is 2 U. S. C. § 192. It provides: “Every person who having been summoned as a witness by the authority of either House of Congress to give testimony or to produce papers upon any matter under inquiry before either House, or any joint committee established by a joint or concurrent resolution of the two Houses of Congress, or any committee of either House of Congress, willfully makes default, or who, having appeared, refuses to answer any question pertinent to the question under inquiry, shall be deemed guilty of a misdemeanor, punishable by a fine of not more than $1,000 nor less than $100 and imprisonment in a common jail for not less than one month nor more than twelve months.” 2 U. S. C. § 192.
  Rule X of the Standing Rules of the House of Representatives, as amended by the Legislative Reorganization Act of 1946, c. 753, § 121, 60 Stat. 812, 822, 823.
  Rule XI of the Standing Rules (60 Stat. 823, 828). These Standing Rules were specifically adopted by the House, at the beginning of the 85th Congress in 1957 (H. Res. No. 5, 85th Cong., 1st Sess.).
  See Braden v. United States, post, p. 431.
  “Now, sir, I should like to make an explanation to you of the reasons, the pertinency, and the relevancy of that question and certain, other questions which I propose to propound to you; and I do so for the purpose of laying a foundation upon which I will then request the chairman of this subcommittee to order and direct you to answer those questions.
  “The Committee on Un-American Activities has two major responsibilities which it is undertaking to perform here in Atlanta.
  “Responsibility number 1, is to maintain a continuing surveillance over the administration and operation of a-number of our internal security laws. In order to discharge that responsibility the Committee on Un-American Activities must undertake to keep abreast of techniques of Communists’ operations in the United States and Communist activities in the United States. In order to know about Communist activities and- Communist techniques, we have got to know who the Communists are and what they are doing.
  “Responsibility number 2, is to develop factual information which will assist the Committee on Un-American Activities in appraising legislative proposals before the committee.
  “There are pending before the committee a number of legislative proposals which undertake to more adequately cope with the Communist Party and the. Communist conspiratorial operations in the United States. H. R. 9937 is one of those. Other proposals are pending before the committee not in legislative form yet, but in the form of suggestions that there be an outright outlawry of the Communist Party; secondly, that there be registrations required of certain activities of Communists; third, that there be certain amendments to the Foreign Agents Registration Act because this Congress of the United States has found repeatedly that the Communist Party and Communists in the United State's are only instrumentalities of a Kremlin-controlled world Communist apparatus. Similar proposals are pending before this committee.
  “Now with reference to pertinency of this question to your own factual situation, may I say that it is the information of this committee that you now are a hard-core member of the Communist Party; that you were designated by the Communist Party for the purpose of creating and manipulating certain organizations, including the Emergency Civil Liberties Committee, the affiliate organizations of the Emergency Civil Liberties Committee, including a particular committee in California and a particular committee in Chicago, a committee — the name of which is along the line of the committee for cultural freedom, or something of that kind. I don’t have the name before me at the instant.
  “It is the information of the committee or the suggestion of the committee that in anticipation of the hearings here in Atlanta, Georgia, you were sent to this area by the Communist Party for the purpose of developing a hostile sentiment to this committee and to its work for the purpose of undertaking to bring pressure upon the United States Congress to preclude these particular hearings. Indeed it is the fact that you were not even subpenaed for these particular hearings until we learned that you were in town for that very purpose and that you were not subpenaed to appear before this committee until you had actually registered in the hotel here in Atlanta.
  “Now, sir, if you will tell this committee whether or not, while you are under oath, you are now a Communist, we intend to pursue that area of inquiry and undertake to solicit from you information respecting your activities as a Communist on behalf of the Communist Party, which is tied up directly with the Kremlin; your activities from the standpoint of propaganda; your activities from the standpoint of undertaking to destroy the Federal Bureau of Investigation and the Committee on Un-American Activities, because indeed this committee issued a report entitled 'Operation Abolition,’ in which we told something, the information we then possessed, respecting the efforts of the Emergency Civil Liberties Committee, of which you are the guiding light, to destroy the F. B. I. and discredit the director of the F. B. I. and to undertake to hamstring the work of this Committee on Un-American Activities.”
  By contrast, the authorizing resolution that was before the Court in Watkins incorporated by reference the full breadth and generality of Rule XI itself. That resolution simply empowered the Committee Chairman to appoint subcommittees “for the purpose of performing any and all acts which the Committee as a whole is authorized to do.” See 354 U. S., at 211, n. 50.
  . . [T]he Committee on Un-American Activities is continuously in the process of accumulating factual information respecting Communists, the Communist Party, and Communist activities which will enable the committee and the Congress to appraise the administration and operation of the Smith Act, the Internal Security Act of 1950, the Communist Control Act of 1954, and numerous provisions of the Criminal Code relating to espionage, sabotage, and subversion. In addition, the committee has before it numerous proposals to strengthen our legislative weapons designed to protect the internal security of this Nation.
  “In the course of the last few years, as a result of hearings and investigations, this committee has made over 80 separate recommendations for legislative action. Legislation has been passed by the Congress embracing 35 of' the committee recommendations and 26 separate proposals are currently pending in the Congress on subjects covered by other committee recommendations. Moreover, in the course of the last few years numerous recommendations made by the committee for administrative action have been adopted by the executive agencies of the Government.”
  See note 5, supra.
  The trial testimony on this score was as follows: “In essence the information of which the committee was possessed was that Mr. Wilkinson was a member of the communist party, that he had been identified by a creditable witness under oath before the committee a short time or within a year or so prior to the Atlanta hearings, identified as a Communist. It was also the information of the committee that Mr. Wilkinson had been designated by the Communist hierarchy in the nation to spearhead or to lead the infiltration into the South of a group known as the Emergency Civil Liberties Committee which itself had been cited by the Internal Security Subcommittee as a communist operation or a communist front. It was the information of the committee that Mr. Wilkinson’s assignments, including setting up rallies and meetings over the country for the purpose of engendering sentiment against the Federal Bureau of Investigation, against the security program of the government, and against the Committee on Un-American Activities and its activities. Mr. Wilkinson had in the course of the relatively recent past prior to his appearance in Atlanta been sent into Atlanta by the communist operation for the purpose of conducting communist activities in the South and more specifically in the Atlanta area. What I’m telling you now is only a general summary, you understand.”
  Since both the pertinency of the question and the fact that its pertinency was brought home to the petitioner are so indisputably clear, we need not consider the Government’s contention that the record does not show that the petitioner ever did or said anything that could be understood as-an objection upon grounds of lack of pertinency. See Watkins v. United States, 354 U. S. 178, 214-215; Barenblatt v. United States, 360 U. S. 109, 124.
choices: First Amendment, miscellaneous (cf. comity: First Amendment) commercial speech, excluding attorneys libel, defamation: defamation of public officials and public and private persons libel, privacy: true and false light invasions of privacy legislative investigations: concerning internal security only federal or state internal security legislation: Smith, Internal Security, and related federal statutes loyalty oath or non-Communist affidavit (other than bar applicants, government employees, political party, or teacher) loyalty oath: bar applicants (cf. admission to bar, state or federal or U.S. Supreme Court) loyalty oath: government employees loyalty oath: political party loyalty oath: teachers security risks: denial of benefits or dismissal of employees for reasons other than failure to meet loyalty oath requirements conscientious objectors (cf. military draftee or military active duty) to military service campaign spending (cf. governmental corruption): protest demonstrations (other than as pertains to sit-in demonstrations): demonstrations and other forms of protest based on First Amendment guarantees free exercise of religion establishment of religion (other than as pertains to parochiaid:) parochiaid: government aid to religious schools, or religious requirements in public schools obscenity, state (cf. comity: privacy): including the regulation of sexually explicit material under the 21st Amendment obscenity, federal