The present study examined whether academic motivations, conceptualized from the stance of self-determination theory, fluctuate over time in a homogeneous or heterogeneous fashion during a school transition. Three objectives were pursued: First, motivational trajectories were studied using the conventional, homogeneous approach. Second, the group-based, semiparametric approach to developmental trajectories was used to study heterogeneous motivational trajectories. Third, family factors were compared across trajectory groups for each type of motivation. Results suggested that most types of motivation tend to fluctuate differently over time for distinct groups of individuals. Furthermore, students characterized by problematic motivational trajectories perceived their parents to be less involved in their scholastic work and less autonomy supportive than those of other students. Results are discussed in terms of their implications for research and theories on motivation and parenting