This report analyses international financial institutions' energy portfolios, identifies best practices, and develops an innovative methodological approach to show these organizations how they can adjust their approach to deliver on their mandates to increase economic productivity and meet environmental and social objectives while lowering energy use from fossil fuel sources at least cost. Energy use is both the major contributor to global greenhouse gas emissions and a vital component of both sustainable development and economic growth. Inefficient and high-carbon energy may help address energy security in the short-term but, over the longer-term, its associated climate and health impacts may well reverse any gains and exacerbate the challenges that countries face in meeting their citizens’ material needs at a reasonable cost.