Examined the transition of adolescents from middle school to high school through a longitudinal research design. Consistent with other studies, results indicate that the transition is associated with declines in grade point average and attendance, and that these changes persist or worsen over the course of the freshman year. Life stress and social support from family, friends, and school personnel each showed expected relationships with some outcome variables, though these varied in pattern and magnitude. Furthermore, there was some indication that these sources could be used in multivariate analyses in assessing their relationship to outcomes. Finally, means-ends problem-solving skills did not predict levels of posttransition support. Results are seen as supporting a differential model of the role of individual and environmental resources in the high school transition, especially with regard to the negative changes in grades and attendance and the pattern of correlations between social support sources and outcomes.