Citizen co-investment in wind energy projects has recently received a lot of attention among scholars and policymakers as a way to finance renewable energy projects and increase community acceptance of these projects. Citizen co-investment refers to the process by which members of the local community can financially participate in renewable energy projects prior to or shortly after construction. While previous research has often been cross-sectional and focused on the preferences of citizen-investors, this paper focuses on the perspective of project developers and asks why, when and how they offer citizens the opportunity to co-invest in wind farms. The work is based on the analysis of fourteen in-depth interviews with a sample of experienced German wind energy developers. The analysis shows that the decision to offer co-investment is driven by citizen demand and local stakeholder preferences, rather than financial needs. We shed light on how experienced developers deal with key trade-offs in terms of the timing of their offering and the choice of capital structure. As a result, we offer a number of testable propositions for further research on the nuanced relationship between citizen co-investment and social acceptance and derive recommendations for policymakers.