This paper exposes the impact of competitive grant funding on public sector nonprofit volunteer organisations, using institutional theory to explain developments within this sector. A conceptual model is developed from which five propositions are derived. Bushcare units, in experiencing institutional pressures, respond in ways that affect their culture, structure and routines, resulting in the possibility that their mission will be compromised. In the process of targeting competitive grants, preparing grant applications, managing increased reporting requirements and recruiting volunteers, Bushcare units should apply a mission “filter” to ensure their mission is not compromised in the pursuit of money. Bushcare New South Wales (NSW), an Australian environmental organisation, provides an empirical illustration of the proposed conceptual model.