The twin benefits of improving environmental quality and reducing tax distortions through the recycling of environmental tax proceeds prove an attractive policy objective. This book analyzes the use of the double dividend concepts for evaluating ecological tax reforms. The author aims to analyze unilateral environmental policy measures thoroughly and to assess under which conditions a double dividend can be achieved. The analysis is undertaken in the context of international capital mobility and cross-border externalities. The book also includes a discussion of an empirically relevant example for an ecological tax reform scenario in Germany - the DIW proposal.