The New York City Department of Health and Mental Hygiene partnered with the nation's largest university system, the City University of New York (CUNY), to provide technical assistance and resources to support the development and implementation of a system-wide tobacco-free policy. This effort formed one component of "Healthy CUNY"--a larger initiative to support health promotion and disease prevention across the university system and resulted in the successful introduction of a system-wide tobacco-free policy on all CUNY campuses. Glassman et al ("J Am Coll Health". 2011;59:764-768) published a blueprint for action related to tobacco policies that informed our work. This paper describes the policy development and implementation process and presents lessons learned from the perspective of the Health Department, as a practical case study to inform and support other health departments who may be supporting colleges and universities to become tobacco-free.