The positive effect of income on volunteering found in many studies is conventionally explained in utilitarian terms: volunteer work is “costly” or demands “resources.” This explanation overlooks important sociopsychological processes. By situating the income‐volunteering relationship within the stress process framework, we develop a theory that traces the influence of income on chronic financial strain which in turn affects subjective well‐being, which functions as a psychological resource for volunteers. Data taken from two waves of the National Survey of Midlife in the United States confirm this theory: household income has no direct effect on volunteering once chronic financial strain and two measures of subjective well‐being—social and eudaimonic—are taken into account.