This paper describes three major theoretical perspectives in research on volunteering: social theories that stress the importance of context, roles, and integration; individual characteristic theories that emphasize values, traits, and motivations; and resource theories that focus on skills and free time. It unites research from multiple disciplines into a single hybrid model, performs a preliminary test of the model on a nationally representative US dataset, and concludes with recommendations for scholars and practitioners. Using the 1995 Midlife in the US dataset, we operationalized concepts from each theoretical category and found that variables measuring each perspective played a substantial and independent role in predicting volunteering. Our hybrid model, which includes significant variables from each theory, offers some directions for recruitment and retention by showing how social roles and networks can constrain or encourage volunteering at different stages of the life course. As social roles and networks are both highly predictive and easily observed, volunteer managers can use them to recruit and retain volunteers. Copyright © 2011 John Wiley & Sons, Ltd.