In recent years, many museums across the country have established or invested resources to implement maker programs or makerspaces for their visitors. These programs and spaces serve a variety of organizational and/or programmatic goals, but fundamentally they serve as sites of learning. Yet, despite these growing efforts, the field knows relatively little about how to support learning within these spaces. This paper presents a framework to inform the design and organization of maker programs and spaces. This framework was developed through a process of visiting makerspaces, interviewing maker educators and researchers and receiving feedback through a series of workshops. The framework consists of three elements: purpose, people, and pieces and parts. By engaging in these elements, we claim that museums can foster the conditions for learning to unfold within maker-based learning experiences.