The EU is subscribing to the international trend of local governments becoming more involved in climate change policy-making and higher levels of government encouraging this trend. With the Covenant of Mayors, the EU has already been successful in voluntarily committing city authorities to reduce their CO2 emissions by at least 20% by 2020. The ambition of the Smart Cities Initiative is to speed up the transition towards local sustainable energy systems. A portfolio of smart cities that represents the population of European cities should be selected, consisting of cities with different energy fundamentals, a different political economy, and different institutional capacities. The cities in this portfolio need to be given the institutional flexibility (human and financial resources) to conceive and manage the implementation of concepts of city smartness, i.e. to lead by example (first level of city smartness: city as a public actor), to govern the actions by the private urban actors (second level of city smartness: city as a local policy maker), and to promote an integrated approach (third level of city smartness: city as a coordinator). To have an impact, the initiative needs to establish a strict performance reporting methodology (currently, city pioneer experiences are difficult to compare or replicate because of a lack of reporting, and pioneers that do report, use very different reporting methodologies), which would allow the creation of a good-practice forum or register. An EU level legislative initiative to require all cities to report about their progress or lack of progress is also recommended to further improve the impact of the initiative.