Energy subsidies are widespread, but they vary greatly in importance and type according to the fuel and country. As these subsidies can cause both positive and negative effects, governments need to take account of national and local circumstances in reforming subsidy policies or designing new ones by meeting the key criteria: well-targeted, efficient, soundly based, practical, transparent, and limited in time. This UN Environment report analyzes evidence from the case studies of the net environmental effects of introducing or removing energy subsidies.