Supporting community food production is a key strategy for all the community-based partners in Food Dignity, a community-university research partnership dedicated to supporting and learning from food justice organizations. Participatory action research (PAR) may develop knowledge and skills for sustainable agriculture, thus building gardeners’ capacities to refine, implement, and share locally appropriate, sustainable food production practices. However, little research has explored the possibilities and challenges of PAR with urban gardeners. In the context of Food Dignity, I examine those possibilities in a case study of a PAR project on cover crops with gardeners in Brooklyn, New York, USA. I address two questions: (1) How can PAR be designed in an urban community gardening context to achieve positive outcomes for science, education, and communities? and (2) What are the challenges, and how might facilitators address them? Several practices contributed to positive outcomes in our project. First, engaging gardeners in cover crop monitoring strengthened their knowledge of ecological processes (e.g., nitrogen fixation) and adaptive management skills (e.g., systematic observation). Second, facilitating opportunities for participants to share their knowledge (e.g., field days) supported leadership development. Third, sustained, in-person support enabled gardeners to implement cover cropping practices with benefits for crop production and environmental quality. Key challenges included addressing community-defined priorities within the constraints of a dissertation project and providing sufficient one-on-one research and education support with limited funding for community-based partners. Despite its challenges, PAR in urban gardening contexts may develop knowledge and skills that support improved stewardship practices and community capacities. Implications for inspiring and sustaining more community-university research partnerships include strengthening institutional support for PAR at colleges and universities, funding community researcher/educator positions, and providing professional development for community and academic PAR partners.