The Matrix Language Hypothesis states that those grammatical procedures in the central structure in the language production system which account for the surface structure of the Matrix Language + Embedded Language constituent (linguistics) are only Matrix Language–based procedures. Further, the hypothesis is intended to imply that frame-building precedes content morpheme insertion. A Matrix Language can be the first language of the speaker or the language in which the morphemes or words are more frequently used in speech, so the dominant language is the Matrix Language and the other is the Embedded Language. A Matrix Language island is a constituent composed entirely of Matrix Language morphemes.