Chronic diseases, obesity and sedentary lifestyles are some of the health challenges facing Canada today. There is increasing recognition and evidence that the way our cities are planned, designed and built can contribute to these problems. Many of the policy levers to address the built environment exist outside the health sector and at the municipal level in areas such as urban planning, transportation, parks and recreation, and housing. The challenge for the public health sector is to build and sustain partnerships and collaboration across various sectors to ensure that health is considered in built environment policies. As the public health unit for the city of Toronto and part of the municipal government, Toronto Public Health is in a unique position to provide leadership, advocacy and support for healthy municipal public policies related to the built environment. This article provides some examples of CLASP (Coalitions Linking Action and Science for Prevention) initiatives undertaken to help create support for healthy public policies in the built environment and suggests that the "Healthy Cities" approach is a useful framework to promote policy change in the built environment at the municipal level.