Purpose: This study tested a theoretical model of volunteering benefits and examined the mechanism through which volunteering benefits older adults. Design and Methods: This is a 2-wave study of 253 older adult volunteers serving in 10 volunteer programs. Older volunteers completed the mailed surveys in 2005 and 2006. Structural equation modeling was used to define the latent variables and to test direct and indirect relationships among organizational support, socioemotional benefits, and self-reported health. Results: Organizational support (measured by choice of volunteer activity, training, and ongoing support) had significant direct associations with 2 latent factors of socioemotional benefits, that is, perceived contribution and personal benefits. Perceived contribution was significantly related to mental health. Additionally, older volunteers with lower socioeconomic status (SES) committed more hours and perceived more personal benefits than higher SES peers. Implications: These findings suggest that volunteer programs can provide various organizational supports to older volunteers, especially to low-SES volunteers, in order to promote the socioemotional and health benefits of volunteering to older adults. Psychological well-being of older adults can be improved through engagement in meaningful volunteer activities and contribution to others.