Preterm birth (<37 weeks’ gestation) is sometimes associated with poorer outcomes in adulthood (e.g., poorer health, fewer intimate relationships, and lower income). However, few studies have examined how these adults felt about their lives or how personality affected these associations. 11,592 preterm and 51,460 full term adults completed online surveys measuring their subjective well-being (life, relationship and job satisfaction, and health). Adults born preterm reported similar levels of relationship satisfaction, but poorer health, life satisfaction and job satisfaction. Adults who reported having long hospital stays at birth also reported poorer health, life, relationship and job satisfaction, and this poorer well-being appeared to be accounted for, in part, by factors such as their personality.