Reading comprehension can be described as the result of a successful interaction of a reader with a text. Schema theory and linguistic theory are valuable for what they have to say about the parties to that interaction. Both bodies of theory have influenced cognitive psychologists' descriptions of the mental processes involved in comprehension (cf. Richgels, 1982). A brief description of each will provide some "prior knowledge" to make understanding of Kintsch's model of comprehension easier.
Richgels, D. J. (1984). Dispelling the Mystery about Comprehension: Kintsch's Model and Implications for Instruction. Reading Horizons, 24 (3). Retrieved from http://scholarworks.wmich.edu/reading_horizons/vol24/iss3/5