These five issues of "Research in Developmental Education," examine the theoretical models and foundations of developmental education. Included are the following: (1) "Theoretical Foundations of Developmental Education," by Hunter R. Boylan, which examines the behaviorist, humanist, and developmental theories underpinning developmental education; (2) "Models of Student Development, Parts I and II" by Boylan, which examine Erikson's Eight Stages of Man and reviews the implications of this human development model for developmental educators; and discuss Chickering's Seven Vectors of Student Development as well as the ways in which those vectors affect students; (3) "A Cognitive Approach to Issues in Developmental Education," by M. Jan Mickler, which examines and critiques cognitive models of learning, including the factorial, developmental stage, heuristic, taxonomic, and integrative models; the article includes an 83-item bibliography; and (4) "Affective and Cognitive Features of Collaborative Learning," by Kate E. Sandberg, which reviews collaborative and cooperative learning theories, describes an integrated model combining elements of both learning strategies, and describes the benefits of this model for students. (PAA)