In the absence of large scale Australian studies of volunteering among older adults, this study compared the relevance of two theoretical approaches--social capital theory and sociostructural resources theory--to predict voluntary activity in relation to a large national database. The paper explores volunteering by older people (aged 55+) in order to assess differences in volunteering in the Australian context. A model was developed that comprised social capital variables (organizational membership, religious affiliation, marital status, and migrant status) and sociostructural variables (education, work status, income, gender, and health status). Logistic regression analyses assessed the relationship between these variables and volunteering, and the interaction effects with two key factors relevant to the Australian context, age cohort and locality. Overall, these results suggest (a) that reliance on bivariate analysis for understanding volunteering may hide a more complex picture associated with older people volunteering, and (b) that neither social capital theory nor sociostructural resource theory adequately predicts volunteering by older Australians, but that generational theories may provide added strength to future analyses. (Contains 2 tables.)