Calls have been made for a greater focus on successful development and how positive functioning can be conceptualized in theory and empirical research. Drawing on a large Australian community sample (N = 890; 61.7% female), this article examines the structure and stability of positive development at two time points during young adulthood. Previously, we developed and empirically tested a model of positive development at 19-20 years comprised of five first-order constructs (civic action and engagement, trust and tolerance of others, trust in authorities and organisations, social competence, and life satisfaction) and a second-order positive development construct. In the current study, we replicated this model at 23-24 years and found that it was again a good fit for the data, and was equally applicable for young men and women. Hence, positive development can be conceptualized according to five important dimensions at both ages. While variable-oriented tests suggested continuity in levels of positive development, person-oriented analyses revealed four distinct patterns of positive development over time--two reflecting stability (stable high [34.5%] and stable very low [11.6%]) and two characterized by change (low/average increasing [30.4%] and average decreasing [23.5%]). There were significant differences in the gender composition of these groups, with young women overrepresented in the more favourable groups. Thus, despite mean level stability, positive development is characterized by change for many young people, suggesting the importance of identifying factors that support young people's capacity for positive functioning over this transitional period. The current findings contribute to our understanding of the nature and course of positive development over this important period.