Objective: This study sought to determine whether social integration, defined as number of social roles, is associated with better pulmonary function in the elderly and which roles are associated with greatest benefit. It also examined pathways that connect social integration to better lung health. Methods: High functioning men (n = 518) and women (n = 629) ages 70–79 were recruited as part of the MacArthur Study of Successful Aging, and data were collected on social roles as well as pulmonary function as assessed by peak expiratory flow rate (PEFR). Multiple regressions predicting PEFR from the number of social roles controlled for age, sex, race, education, weight, and height. Physiological, behavioral, social, and psychological factors were tested as mediators of the association between the number of social roles and PEFR. Results: More social roles were associated with better PEFR. Analysis of specific roles indicated that marriage was the strongest positive correlate of PEFR. However, greater numbers of roles were also associated with better PEFR independent of marriage. Being a relative or friend were each also individually associated with better PEFR. Even so, greater numbers of social roles were associated with better PEFR independent of relative and friend. The data were consistent with greater happiness, not smoking, and more physical activity acting as pathways linking the number of roles to PEFR. Conclusions: Number of social roles is an important correlate of healthy lung function in the elderly. This association may be driven by healthier behaviors and greater feelings of well-being.