Revenue volatility hinders the planning within nonprofit organizations, and as a consequence, it can influence the organization’s contribution to public welfare. To analyze the extent of revenue volatility and its determinants, this paper uses a comprehensive, longitudinal, data set of German nonprofit sports clubs (n = 724). It distinguishes between systematic volatility and club-specific volatility, and argues that a complete understanding of the sources and impacts of volatility requires one to clearly distinguish between the two components. Empirical results indicate that revenue diversification can significantly reduce club-specific volatility, but has more minimal benefits for lowering systematic volatility. It also reveals that clubs that rely more heavily on membership fees, and less on subsidies, appear to have reduced levels of systematic and club-specific volatility, with the impact being much greater for the latter.