SummaryTo account for the semanties of complement constructions requires meaning properties that are not restricted to individual lexical items and their sense relationships. In dealing with subject and object sentences one has to pay attention to semantic properties that define a subordinate clause in relation to the predicate of the main clause. The distinction between factives and implicatives, which has been drawn in recent studies on English complement constructions boils down to the question originally asked by Frege whether the complement is semantically a sentence or not. In case it is Frege distinguished between two groups. Sentences which have the truth value for their reference and sentences which have the truth value for their presup‐position. In case it is not the complement sentence has no reference at all. Factive and implicative predicates differ in that complement sentences of the former constitute a sentence semantically the truth value of which is its presupposition, while the latter do not. This difference shows up in various restrictions on operators like negation, tense, time and locative adverbials. Whereas the complement of an implicative falls within the scope of the operator of the main clause predicate, the order of main clause predicate and complement is reversed for factive