Background: Life history theory provides a unifying perspective on understanding human behaviors as adaptive strategies in response to particular environmental conditions. There is little empirical literature on the relationships between life history strategies and positive youth development. Objective: This study examines the relationships between environmental certainty, life history strategies and external and internal developmental assets among adolescents. Methods: Participants were 577 adolescents (53.5% boys) from Shanghai, China. Data on environmental certainty, life history strategies and developmental assets were collected from adolescents' self-reports. Results: Adolescents with a slower life strategy reported higher levels of both external and internal assets. Furthermore, perceptions of environmental certainty were associated with both external and internal assets through a slower life history strategy. Conclusions: Developmental assets may be a part of or the result of the slow life history strategy in response to certain environments. This pattern also complements and expands previous findings linking life history strategy and negative adolescent development. The present study suggests profitable avenues of study in the areas of social environments and positive youth development.