Studies of self-directed learning (SDL) have generally concentrated on who self-directed learners are and what/how they learn. In 1980, Gibbons et al. used biographies of 20 "expert" self-directed learners to explore the principles and determinants of SDL. Tough (1967), Guglielmino (1977), and Spear and Mocker (1984) have respectively characterized SDL as primarily a pedagogical variable, psychological variable, and systemic variable. In so doing, they have successively shifted the focus of research on SDL from the learning project to the individual learner and to the circumstances surrounding SDL activities. In addition, the following three paradigms may be associated with mainstream literature in the field of SDL: (1) the contingency control paradigm, according to which the determinants of SDL are contingent upon external forces; (2) the psychodynamic paradigm, which focuses on behavior as a response to needs, inner impulses, and innate instincts; and (3) the systemic paradigm, according to which human experiences/activities (including SDL) are inseparable from the myriad factors and events constituting a person's past and present "life field." Together, these three paradigms can serve as a framework for classifying individuals' explanations of why and how they came to acquire their professional skills in a self-directed manner. (Contains 32 references.) (MN)