As volunteerism occurs in an organizational context, both individual factors and organizational characteristics affect (potential) volunteers in sports clubs. Whereas a number of researchers have studied individual-level determinants, knowledge on the role of organizational-level factors is limited. Based on the concept of organizational capacity, in the present study, the authors investigate whether and how human resources, financial, and structural capacities of sports clubs influence individual voluntary engagement. Using data from German football and track and field clubs (n = 296) and their members (n = 1222), the effects of organizational capacity on voluntary engagement within two subsamples, adult members and parents of underage members, are examined. The results of multi-level mixed effects regression analyses show that all capacity dimensions are significantly associated with voluntary engagement of both adult members and parents of underage members. A larger number of members and a greater share of volunteers reduce the amount of time a volunteer devotes to voluntary work; adult members are less likely to volunteer when their club has a balanced budget; and strategic planning increases the likelihood of individuals to volunteer informally. Overall, the results support the notion that the organizational context is more relevant to volunteering of adult members than individual characteristics and equally relevant to parents of underage members. Managerial implications to facilitate volunteering, such as shifting club goals towards youth development and sports for all provision, are discussed. (C) 2017 Sport Management Association of Australia and New Zealand. Published by Elsevier Ltd. All rights reserved.