A number of syntactic constructions claimed by linguists to be restricted to main clauses are shown to occur, in fact, in a variety of subordinate clause types, but only under certain mysterious conditions—basically, when the speaker desires to be understood as committed to the truth of the subordinate clause. Formalization of this notion, however, remains elusive. The analysis of this phenomenon by Hooper & Thompson 1973, while attractive and initially explanatory, is shown to be, before the final analysis, incapable of accounting for the range of embedding environments allowed, which differs from one restricted construction to another. It is shown in the present paper that an adequate solution will involve a complex interaction of several factors—syntactic, semantic, and pragmatic—and the range of data to be accounted for is partially delineated.