In April 2018, a three-day workshop entitled "Citizen Science and the Food System" took place in Honolulu, Hawai'i (USA). The ten professional scientists and six community-based investigators who participated have diverse practical experiences with citizen science (CS) covering a range of food and farming issues. This report summarizes the discussions that took place and provides suggestions to researchers, university administrators, and funding bodies on how to support agri-food research that engages a wide range of collaborators. Workshop participants shared their experiences and articulated the lessons they have learned about fostering research partnerships in the food system and the challenges that can undermine participatory research. Attention to social and historical contexts is crucial. Many aspects of the agri-food system have been built on the dispossession of indigenous peoples, and food production and distribution is highly stratified by race, ethnicity, class, and citizenship. Large corporations have significant power over the norms and practices of food production, distribution, and consumption. The pursuit of "food justice" through CS requires diligent attention to these power asymmetries and concerted efforts to redistribute power. Workshop participants also drew attention to the need for various forms of support for CS projects relating to food and agriculture. Funding is, of course, a key challenge, but academic/university expectations also hinder participatory research.