REDD+ Subnational Initiatives examines how REDD+ projects canbe designed and implemented so that their outcomes are effective, effi cient and equitable and they deliver co-benefi ts. Although REDD+ is still being negotiated in international arenas, some 200 subnational forest carbon initiatives are already underway around the world.1 These interventions aim to increase forest carbon stocks relative to business-as-usual scenarios (i.e., the scenario if there were no intervention). How successful are these interventions likely to be? Will their outcomes be effi cient, equitable and effective? Will they deliver co-benefi ts such as improved livelihoods and protection of rights, tenure and biodiversity? What conditions and activities help or hinder these projects in achieving their aims? How can they get the necessary support from local people? To help answer these questions, we collect and analyze socioeconomic and biophysical baseline data at 23 REDD+ project sites in six countries, encompassing more than 170 villages and nearly 4000 households. To ensure effects are appropriately attributed to the projects, we compare data before and after, and with and without, an intervention.