This report lays out a roadmap for doubling global hydroelectricity production by 2050, noting that since 2005 new capacity additions in hydropower have generated more electricity than all other renewables combined. It highlights that the potential for additional hydropower remains considerable, especially in Africa, Asia and Latin America. Indeed, most of the growth in hydroelectricity generation is anticipated to come from large projects in emerging economies and developing countries. Hydropower’s ability to regulate water flow may also be useful to climate change adaptation. However, the report acknowledges that hydropower requires large up-front investment and calls for innovative financing schemes and market design reforms to ensure adequate revenue flows. Governments are urged to take the lead in encouraging industry investment. Required actions relate to the policy and market framework, sustainability and public acceptance, financial challenges and technology development.