For the “Montréal en commun” programme by the City of Montreal, a participatory evaluation was undertaken with four organizations of the alternative food system. This undertaking, which included three workshops and coaching sessions, was to develop tools to assess the impact of the projects; to contribute to knowledge and capacity acquisition for continuous improvement in the organizations; and, generally, to test assessment practices that could be replicated on a larger scale in the Montreal food system. The results are a “theory of change”, a series of 70 indicators to evaluate the projects and their spin-offs, and a collective evaluation plan. Moreover, a reflexive summary and semi-directed interviews with participants in the undertaking, have allowed us to document the learnings from this experimentation of a participatory evaluation for alternative food projects.