The purposes of this article are to analyze the concept of literacy in order to identify measurement problems associated with specifying each of these parameters, and to describe literacy assessment procedures now available for dealing with measurement problems. The principal focus of the paper is on the development of models for identifying performance criteria that can serve as the goal of instructional programs and of the research and development programs that lead to them. The five parameters discussed are the classes of literacy behaviors, the level of performance that serves as the criterion of literate performance, the kinds of reading tasks on which the behaviors are tested, the proportion of the reading tasks that serves as the criterion of literacy on some corpus of reading tasks, and certain characteristics of the prople tested, such as the levels of aptitude and perseverance represented within it. (Author/WR)