On October 23, 1956, a banquet in Cain's honor was held at the National Press Club and attended by more than 350 civil liberties advocates, labor leaders and political admirers, including many of the individuals who Cain had helped. A plaque was presented to Cain with the following inscription: "In Tribute to Harry P. Cain / Champion of Human Dignity, Defender of Constitutional Rights in the Search For National Security / From Those Whose Loyalty to Country He Vindicated, and Those Whose Faith in Freedom He Strengthened / Presented at Testimonial Dinner / National Press Club, Washington, D.C. / 23 October 1956."