Cities are widely seen as an effective arena for climate change policy because of the high concentration of greenhouse gas (GHG) producing activities that occur within them. In both the United States and China,new municipally based GHG mitigation initiatives have emerged during the past several years,signally a shift away from top-down,internationally organized climate change efforts. In the US,for example,more than 1,000 local governments have voluntarily agreed to reduce their GHGs through the US Mayors Climate Protection Agreement. In China,low carbon cities are being promoted as an ideal pathway for future urban development. As China embarks upon the integration of carbon-related policies and urban development,lessons from the US context will be particularly relevant. This paper will discuss how and why local governments in the US have created and implemented local climate change programs. Many US cities emphasize the importance of economic incentives and co-benefits in the justification of local climate action,while new methods of quantifying and monitoring climate-related efforts have also proved to be an effective policy mechanism. Serious limitations of local climate programs have also been noted in the US context,including their reliance on voluntary changes in individual behavior and their focus on public sector buildings and infrastructure over private development. The successes and limitation of the US approach to urban climate governance will then be considered in relation to the China context,including what key differences in GHG emissions profiles exist and how strategies for efficient and equitable distribution of GHG reductions among various sectors can be achieved. Increasing the capacity of local governments to create the low carbon cities of the future,while also promoting social justice and economic development,is essential for both the US and China to truly reduce their GHG emissions.