Despite a rich literature on organizational capacity (OC) in voluntary sports clubs (VSCs), few studies have examined OC building and its long-term sustainability. Against this background, the authors identified changes in OC among VSCs that participated in a club development program and examined the sustainability of these changes. The authors collected survey data 9 months after participation comparing the participating VSCs (n = 62) with similar nonparticipating VSCs (n = 64). A selection of the participating VSCs was then contacted 3–4 years later for a follow-up survey (n = 48) and focus group interviews (n = 5). The results show that (a) significant differences in human resource capacity, planning and development capacity, and infrastructure and process capacity were visible between the participating and nonparticipating VSCs, and that (b) certain changes in OC remain in the clubs 3–4 years after participation. A sustainable change was that core volunteers related differently to the work in their respective VSCs.