Information necessary to understand many English sentences appears to be supplied by a source outside the sentence which is composed of a fund of knowledge accumulated throughout life. This fund of knowledge may be visualized and a conceptual network into which the incomplete information supplied by a sentence can be mapped, thus making it possible for the reader to fill in the missing pieces of the conceptual situation designated by the sentence. Such a conceptual network would seem to be the source, also, of the various kinds of expectation concerning the contents of those parts of the sentence which the reader has not yet read which help the reader to resolve lexical and relational ambiguities. A greater awareness of this function of the reader's conceptual universe might lead to an improvement of instructional and remedial strategies for the teaching of the interpretative language skills. References are included. (Author/MS)