Food waste is a major challenge in affluent societies around the globe. Based on theories of protest and a mixed methods design combining qualitative, experimental, and survey research, we study the motives for, frequency of, and public support for dumpster diving in Germany. We find that dumpster diving as an unconventional daily protest action is related to more general protest against capitalist societies. It is motivated by both altruistic and egoistic concerns. The perceived legitimacy of violence and self-identity explain the frequency of dumpster diving. A factorial survey experiment with activists and the general public reveals strong similarities between the views of activists and those of other citizens in strong support of dumpster diving. This study demonstrates the usefulness of combining different empirical methods to study food activism.