The SUMPs-Up project is developing an innovative acceleration mechanism for the widespread up-take of Sustainable Urban Mobility Plans (SUMPs) throughout Europe. The project uses a four-step approach (validate, systemise, accelerate and secure) to ensure that the SUMP becomes Europe’s leading mobility planning approach. Improving the efficiency of urban transport while mitigating its negative effects and enhancing the attractiveness of Europe’s urban centres requires a strategic planning approach. Research has shown that SUMPs can greatly improve urban liveability, with better public spaces, less pollution, and stronger local economies. Through its acceleration mechanism, SUMPs-UP is supporting the development of 100 new SUMPs and is providing support and resources to almost 80% of European cities with more than 50,000 inhabitants, making it one of the EU’s most wide-reaching and influential SUMP projects.