Purpose: This paper describes the sustainability partnership between the City of Vancouver and the University of British Columbia (UBC) and, in particular, the co-curricular Greenest City Scholars graduate student internship program, which has been developed by the two organizations. Through the program, UBC graduate students work on projects at the City that help to advance sustainability targets. The paper aims to explore the successes, challenges and lessons learned from the program. Design/methodology/approach: This case study uses literature and document review, observations, program participant evaluation surveys and project impact survey feedback. Findings: The Greenest City Scholars program model has contributed to the sustainability goals at UBC and the City of Vancouver and has supported the partnership between the two organizations. The program has grown over its five-year history and is considered to be a central part of the partnership. Breadth of student participants from across the university and high participation from City departments have been achieved. The model is now being adapted to be delivered within other partnerships. Practical implications: The experiences presented in this case study can help other higher education institutions understand how a co-curricular graduate student work experience program could help to bolster their own sustainability partnerships. Originality/value: This paper makes a contribution by providing insight into the use of a graduate student program to advance the goals of a university-community sustainability partnership.