The present study investigated the developmental trajectories and the possible antecedents (e.g., gender, school track, academic achievement, self-esteem, parental affect, and monitoring) of 17- to 21-year-old young adults’ engagement in their studies and work. The study is part of the longitudinal Finnish Educational Transitions (FinEdu) study involving 804 participants. The results revealed four latent trajectory groups of study and work engagement: high increasing (72%), low increasing (14%), high decreasing (9%), and low stable (5%). High parental affect and high self-esteem among 16-year-old adolescents manifested themselves as an increase in engagement in studies and work during the transition to work or higher education in early adulthood. Moreover, a lower level of parental affect resulted in a decrease in subsequent engagement.