Local health departments (LHDs) have a key role to play in developing built environment policies and programs to encourage physical activity and combat obesity and related chronic diseases. However, information to guide LHDs' effective engagement in this arena is lacking. During 2011-2012, the New York City Department of Health and Mental Hygiene (DOHMH) facilitated a built environment peer mentoring program for 14 LHDs nationwide. Program objectives included supporting LHDs in their efforts to achieve built environment goals, offering examples from DOHMH's built environment work to guide LHDs, and building a healthy built environment learning network. We share lessons learned that can guide LHDs in developing successful healthy built environment agendas.