Entrance into college is considered a stressful experience, with many students experiencing depression and maladjustment. A longitudinal study was conducted to investigate three major models of depression among college students, i.e., the life events model, the cognitive-attributional model, and the social support model. Subjects were 134 freshmen who were questioned at the beginning of their first semester and again 6 weeks later. Results indicated that the variables most strongly and consistently associated with depression were loneliness, interpersonal mistrust, and neuroticism. Data suggested that interpersonal mistrust and neuroticism were related to depression through the variable of loneliness and that loneliness also "caused" interpersonal mistrust and neuroticism. The findings suggest that loneliness is an important cause of depression among college students. (Author/JAC)