Motivation can be undermined among first-year college students as they face a multitude of unanticipated challenges during the transition from high school to college (Compas, Wagner, Slavin, & Vannatta, 1986; Perry, Hall, & Ruthig, 2005). As a consequence, approximately 27% of first-year students do not return for the second year of college (Feldman, 2005). First-year college students (N=336) participated in a study to examine the efficacy of an Attributional Retraining (AR) treatment designed to increase motivation and enhance academic achievement. Employing a pre-post study design spanning an academic year, we examined the impact of AR on student motivation as operationalized in terms of mastery and performance goals. Findings indicated that AR increased mastery motivation but did not affect performance motivation. Findings also demonstrated that mastery motivation mediated the relationship between AR and grade point average, suggesting that mastery motivation is a key mechanism of AR. Findings are discussed in terms of conceptual contributions to both the AR and achievement motivation literatures, and practical implications are outlined.