Based on an accelerated longitudinal design involving three cohorts of secondary school students followed during 3 consecutive school years, this study had three main objectives. First, we sought to identify different profiles of students following distinct trajectories of self-determined motivation over the secondary school years. Second, we examined whether different sources of relatedness (father, mother, teachers, peers) predict membership to these motivational trajectory profiles. Third, we looked at the consequences of these motivational trajectory profiles in terms of adaptive and maladaptive outcomes. Nine hundred forty-one students (56.1% girls) from three distinct cohorts participated in the first measurement time (309 students initially in Secondary 1, 346 students initially in Secondary 2, 272 students initially in Secondary 3). Results revealed that no generic decline in global levels of self-determined motivation was observed during the secondary school years. Five distinct trajectory profiles in which the proportion of students varied were identified. The many comparisons made between these five profiles indicate few significant differences on sources of relatedness. However, teachers and fathers were important positive predictors of membership to the profiles characterized by higher self-determined trajectories, in addition to having a direct effect on initial levels of self-determined motivation observed within each profile (teachers) and on within-profile increases over time in global levels of self-determined motivation (teachers and fathers). Finally, students in profiles characterized by low self-determined motivation trajectories showed lower levels of adaptive outcomes and higher levels of maladaptive outcomes.