This study examines the relationships of volunteering behaviors with work–retirement patterns and transition among middle-aged and older Americans using the Health and Retirement Study data (1998-2008). Latent class analysis was used to identify retirement status and cluster respondents into five latent classes: the not-retired, partial retiree, full retiree, non-worker (e.g., homemakers), and the transitioned (i.e., the newly retired from paid work). Generalized linear mixed models showed those experiencing work–retirement transitions were significantly more involved in volunteering than the not-retired. Partial retirees and full retirees were more likely to start volunteering, and full retirees were also more likely to end volunteering than the not-retired over the 10-year observation period. Volunteer organizations are advised to recruit older adults who have time available and social connections with the workforce and to target the newly retired who are likely to increase their volunteer time during the transition process.