Communities, intended as self-organized informal groups, are much less structured than nonprofit organizations typically considered by Cross-Sector Social Partnership (CSSP) studies. Building on the empirical investigation of a real CSSP, this article offers an in-depth analysis of the ambivalent dynamics implied by partnership with such communities. Our findings indicate that the mechanisms that create room for innovative collaboration opportunities made available by these communities (such as co-innovation, pricing co-determination, co-financing, and democratic decision making) can also, over time, adversely affect the partnership and cause it to permanently lose its shared purpose. In our conclusion, we provide potential remedies for the latter scenario and discuss how they may enrich CSSP literature.