University campuses are dynamic foodscapes that meet the needs of thousands of diverse community members. These foodscapes are difficult to comprehend in their entirety, and inequities based on race, class, gender and gender identity, sexual orientation, dis/ability, and other forms of marginalization often remain unidentified and unaddressed. Since 2015, the UC Berkeley Foodscape Mapping Project has emerged as a model of participatory, justice-oriented food systems education. Drawing on critical pedagogy principles, it uses the Berkeley campus as a living laboratory for students, staff, and faculty to generate food systems knowledge. We trace the project’s development to show how what started as a set of workshops to address campus climate problems grew into a major mapping effort and advocacy projects that aim to improve the campus food system. Early on, workshops found that the biggest barrier to changing our campus food system was understanding the system itself: who the individual and departmental decision makers are and how different parts of the foodscape interact. Foodscape mapping is one possible pathway for changing a campus food system. This pathway was chosen because it could create a much-needed data foundation for advocacy at UC Berkeley. We discuss the concept of mapping and work through the process of building the Campus Food Players map. Several examples of Spotlight Maps and a practical policy advocacy project are presented to show the variety of outputs. Finally, we analyze financial, personnel, and pedagogical resources needed to realize the map, along with important constraints on its development. Readers will learn about campus foodscape mapping and be better equipped to develop projects at their own campuses.