This working paper is a product of a regional study in industrial South Wales of the determinants of participation and non-participation in post-compulsory education and training, with special reference to processes of change in the patterns of these determinants over time and to variations between geographical areas. This paper describes the notion of learning trajectories and considers determinants of an individual's participation in education or training. It discusses a door-to-door survey of 1,104 householders in industrial South Wales to obtain their life work and educational histories that were analyzed to identify trajectories--characteristic patterns of participation and non-participation in post-compulsory education and training. These 5 categories with 11 trajectories are identified: disaffected learner (non-learner, near non-learner); delayed learner (delayed learner, deferred student, twilight learners); transitional learner (false-start trainee, false-start student); immature learner (still at school, still in full-time education); and lifetime learner (work-based learner, early learner). The analysis that led to determination of six predictor variables--area of residence, gender, type of school, attempting qualifications, qualification at age 16, and occupational class of father--is explained. Appendixes include development of learning trajectories. Contains 57 references. (YLB)