Previous research has indicated that pubertal development and the transition from middle or elementary school to junior high may present problems for some preadolescents. The effects of these transitions on achievement, psychological well-being, and social relations were examined using data from the National Longitudinal Survey of Children and Youth. Children were tracked during a 2-year period and the changes in outcome scores were assessed. Results indicate that psychological well-being was closely related to social relations, and socioeconomic status was predictive of achievement and social relations. However, pubertal development and school transition had a minimal impact on outcome. (Contains 3 tables, 2 figures and 3 notes.)