Grand challenges are universal problems in search of scalable solutions such as new business models. However, the effectiveness of solutions depends critically on their fit with the local context. How do social entrepreneurs decide how to adapt existing business models to their contexts? We address this question in an inductive study of Slow Money—a microfinance organization that promotes sustainable food production in the U.S. In investigating how Slow Money adapted the investment club business model to different locations, we find that evaluating the external fit and learning about the internal fit of the business model can serve as substitutes in the process of local adaptation. Our findings shed light on the interplay between cognitive and experiential search in adapting business models to address grand challenges.