A discussion is provided of the distinguishing characteristics of developmental education. First, the reasons for the lack of a clear definition are discussed, and the consequences of this ambiguity are highlighted in terms of the existing confusion over the purposes of developmental education. Next, the linguistic and theoretical bases of developmental education are explored, with particular emphasis on the two major supporting concepts of developmental age and sequential learning. The following section looks at the definitive features of developmental education within postsecondary education, including: (1) institutional and state policies toward the granting of college credit for developmental courses; (2) the characteristics of the two types of developmental students; i.e., the slow learner and the inadequately prepared student; (3) the goals related to content mastery and personal development that have grown from the need and desire to serve this group of students; (4) the special instructional techniques and curricular features that have been applied to achieve program goals; and (5) the special qualities of developmental educators. (HB)