In the first chapter we sketched the rise of modern psycholinguistics out of the historical constellation of postbehaviorist psychology and generative linguistics. We contrasted the working tendencies in linguistics with those in psychology by means of two key phrases: on the one hand, language as a self-contained closed system, on the other, language as a tool used by man. In the past, psycholinguistics worked mainly with concepts that come from this system-oriented linguistics and tried to use these concepts in the psychological explanation of the phenomena of language use as well. Psycholinguistics has tried to establish what was called the "psychological reality" of linguistic concepts and linguistic theoretical assumptions. In this chapter we will present such concepts and theoretical assumptions, as far as they are necessary for our purposes, without further maintaining the division between structural and, in the narrow sense, generative linguistics.