--- - |2 Summary Initial evidence suggests that older workers enjoy higher work–life balance than young workers. Yet little is known about the mechanisms of this effect or the robustness of age differences when accounting for differences in life context. We introduce and test the boundary management account of aging and work–life balance, which suggests that older workers maintain stronger work–nonwork boundaries as a pathway toward work–life balance. Both in Study 1 (cross‐sectional; N = 298 bank employees) and in Study 2 (aggregated diary entries; N = 608 workers), older workers reported better work–life balance and stronger boundaries at work than young workers; and stronger boundaries at home (Study 1). In both studies, stronger boundaries were related to better work–life balance, and boundary strength mediated the relationship between age and work–life balance. Study 2 additionally suggests that the use of boundary management strategies is responsible for stronger boundaries at higher age. Analyses accounted for differences in family and work context characteristics (both studies) and boundary preferences (Study 1). The findings corroborate evidence of older workers' enhanced work–life balance and suggest that it results from more successful boundary management with age rather than merely from changes in contextual factors or boundary preferences. - Journal of Organizational Behavior, EarlyView.