Learning by engaging in the practices of a discipline (practice-based learning) provides museum visitors with opportunities to construct understandings that build on their prior experiences and interests. However, effectively facilitating such learning experiences is difficult. We present a framework that supports facilitators in providing practice-based facilitation, which begins with observations of how visitors engage with an exhibit and expands and deepens visitors' use of disciplinary practices. The framework includes two complementary tools developed through iterative design-based research situated in an interactive science center. The first tool links exhibit-specific observations of visitor engagement to STEM practices. The second tool provides three pathways related directly to the visitor's experience that inform facilitation moves. The framework and associated tools could be modified for institutions focused on other disciplines such as art or history by incorporating the practices that align with the ways professionals in those disciplines construct meaning, engage in analysis, and solve problems.