Part of a research project designed to develop a theory of the cognitive processes involved in skilled reading by the analysis of the location and duration of eye fixations, this paper concentrates on how eye fixations can be used to determine when encoding, lexical access, parsing, and integration processes are executed and how they are affected by various features of text. The paper first discusses the immediacy assumption, which holds that a reader tries to interpret each word of a text immediately upon encountering it, and the eye-mind assumption, which posits that the reader continues to fixate a word until all the cognitive processes initiated by that word have been completed to some criterion. It then reviews several global features of eye fixations in reading that provide support for these assumptions, noting that several run counter to common conceptions of reading. The paper next describes a general model of language comprehension based on a computer simulation that was developed both to formalize models of specific processes and to make the processes function collaboratively in an interactive system. This discussion is followed by a review of research on specific comprehension processes and an evaluation of the model. (FL)