The purpose of this study was to examine how successes and difficulties with various developmental tasks of early adulthood relate to the course of well-being. Three waves of national panel data spanning ages 18-26 were drawn from the Monitoring the Future study (N = 3518). Based on self-reports, respondents were assigned scores (succeeding, maintaining, or stalling) to reflect progress in seven domains of developmental tasks: education, work, financial autonomy, romantic involvement, peer involvement, substance abuse avoidance, and citizenship. We identified trajectory groups of well-being (based on self-esteem, self-efficacy, and social support) that reflect diverging trajectories during the transition: steady-high versus high-decreasing, and low-increasing versus steady-low. Logistic regression analyses were conducted to predict membership in the diverging well-being trajectory groups as a function of developmental task domain scores. Maintaining or gaining a salutary trajectory of well-being across the transition was found to be a function of more success and less stalling across the developmental tasks, specifically in the work, romantic involvement, and citizenship domains. Compensatory effects (e.g., succeeding in education compensated for not succeeding in work) and threshold effects (e.g., succeeding in both achievement and affiliation domains was necessary for a salutary trajectory) were also found.