Sustainability is a concept that has become ubiquitous in sports development policy and practice. Despite this ubiquity, there remains a lack of clarity in practical understandings of the concept of sustainability. Moreover, research on sport and sustainability is limited and lacks theoretical underpinning. This article addresses these problems by proposing frameworks that can be used to examine and understand sustainability in sports development. In particular, two frameworks are developed through synthesising sustainability concepts presented in the literature on health programmes and adapting them to sports development through consideration of recent policies and programmes. The first framework addresses definitional issues by identifying four forms of sustainability that may be addressed by sports development programmes, namely individual, community, organisational and institutional sustainability. The second framework allows classification of processes that affect sustainability according to dimensions that concern the level of control held by agencies responsible for sports development sustainability and the level of integration between processes to achieve desired sports development outcomes and processes to achieve sustainability. Presentation of a case study of sustainability in the New Opportunities for PE and Sport Activities programme in Scotland enables discussion of the applicability of the frameworks to sports development as well as identification of implications that are derived from application of the frameworks. On the basis of this analysis, conclusions are drawn concerning the relationships between different forms of sustainability and the effectiveness of sports development programmes and the types of processes that affect different forms of sustainability. The implications for future research on sports development sustainability are discussed.