Recent developments in cognitive psychology and artificial intelligence have shown that various types of prior knowledge play important roles in understanding during text processing and have resulted in a new kind of model for conceptual processing, "procedural semantics." This paper discusses two types of units, or schemata, which, according to this theory, are responsible for conceptually driven processing in reading: the form-schema accounts for readers' syntactic or formal expectations; the content-schema accounts for readers' semantic expectations. Models for specific form- and content-schemata are proposed; implications for effective strategies for adult reading are derived from the premises of the model; and four kinds of reading strategies (single-pass, exhaustive multi-pass, extractive multi-pass, and selective multi-pass) are characterized in terms of the model. In addition, potential applications, suggested by the consequences of the theory, are described. These include uses for headings in texts, means for constructing advance organizers for texts, and training of readers to make more effective use of texts by being sensitive to their motivating tasks and by exploiting their capacities for generating expectations about the meaning of the texts, through conceptually driven processing. (Author/LJR)