In the Sustainable Mobility Programme 23 municipalities in the Rotterdam–The Hague Metropolitan Area (RHMA) are collaborating on achieving a sustainable region with clean, quiet and low-energy transport. One of the stated aims is to cut the CO2 emissions of the mobility/transport sector by 30% relative to 2015 by 2025. To this end the RHMA organisation and the municipalities have drawn op a policy package comprising 45 measures. This study calculates the projected CO2 impact of these measures and assesses the prospects for securing the regional target by 2025.