Trainees' motivation is an important factor to consider in order to strengthen their learning, wellbeing, and involvement in training sessions. Unfortunately, prior research has often adopted a static (cross-sectional) and unidimensional perspective of training motivation, been limited by the consideration of a very limited range of outcomes, and failed to consider the possible predictors of trainees' motivation. To address these limitations, the present study examines the shape, determinants (autonomy-supportive behaviors), and outcomes (positive and negative affect, fatigue, engagement, learning, and satisfaction) of autonomous and controlled motivation trajectories over the course of a professional training program. A sample of 43 employees completed the measures on four occasions (first day, three weeks, 10 weeks, and 14 weeks) over the course of a 14-week professional training program. This study also relies on a burst design, whereby employees completed each measure twice (with a half-day interval) at each measurement occasion to achieve a more accurate representation of occasion-specific ratings. Results from three-level growth analyses (with the two bursts at Level 1, four occasions at Level 2, and participants at Level 3) showed that autonomous motivation, negative affect, learning, and satisfaction appeared to follow curvilinear trajectories, whereas autonomy support and positive affect followed linear trajectories. In contrast, controlled motivation, fatigue, and engagement levels remained stable over time, consistent with an intercept-only model. Furthermore, higher levels of autonomy support were associated with higher levels of autonomous motivation, and lower levels of controlled motivation over time. Finally, higher initial levels of autonomous motivation predicted higher levels of positive affect, learning, satisfaction, and engagement, and lower levels of fatigue over time, whereas higher initial levels of controlled motivation predicted higher levels of fatigue over time.