Cities have a unique role to play in accelerating the sustainable energy transition. Crisscrossed with transport systems and home to a variety of energy-intensive end-use sectors like heating and cooling, cities are a prime playing field to transition to sustainable energy. More than half the world’s population (55%) lives in cities today, and cities account for two-thirds of global energy demand and around 75% of global CO2 emissions. However, comparable data are lacking on city-level renewable energy targets, policies and action. The Renewables in Cities 2019 Global Status Report is the first in what is to become an annual stock-take of the global transition to renewable energy at the city-level. REN21 is developing this series to build up reliable data on and create a comprehensive picture of renewable energy developments in cities globally. This makes it possible to better inform decision-makers both in cities and in the wider energy arena.