Few empirical studies have focused on young children's happiness (high positive affect and low negative affect) and specifically whether it is related to adult wellbeing. Adult well-being indices (e.g., life satisfaction, workplace hope, and optimism) may have developmental roots in early affect. In the 28-year Fullerton Longitudinal Study (N = 129) we examined positive affect and negative affect as independent constructs during infancy (parent report) and adolescence (self-report) to determine their relationship to global adult life satisfaction (self-report). In addition, we tested the generalizability of the effects of positive and negative affect in relation to domain-specific adult well-being constructs (i.e., workplace hope and optimism), which hold utility for concurrent and prospective well-being. Structural equation modeling revealed that positive affect during infancy and adolescence each uniquely predicted adult life satisfaction. In a separate model for a subsample of employed adults, infant positive affect showed significant positive associations with workplace hope and optimism. Neither infant nor adolescent negative affect predicted any adult well-being outcomes. Our results highlight the need for more developmental studies examining the relationship between children's positive and negative affect and long-term well-being.