Imposed regime changes are a fundamental feature of international politics. Russia's attempt to change Ukraine's regime is ­­­­­­an important example, potentially. Changing regimes in Germany, Japan, and Italy was a principal goal and outcome of World War II. Though at great cost, those regime changes were successful. Russia's struggle to remove the regime in Ukraine encountered unusual obstacles. More typical have been the 21st century projects carried out by the United States and its allies in Afghanistan, Iraq, and Libya. In those cases, eliminating objectionable regimes has been easy. Replacing them has been hard. In Catastrophic Success, Alexander Downes argues that initial success and long-term difficulties have been typical of foreign imposed regime changes. Such changes tend to fall into three main categories. The first is limited to the removal of leaders. The second removes leaders and develops new institutions. The third restores previous regimes. Imposed regime changes tend to lead to civil wars, irregular removal of leaders, or conflict between the interveners and the target state. Changes restricted to new leaders are particularly likely to lead to such undesirable outcomes, especially if they are accompanied by disintegration of the military forces in the targets, or to situations where the new leaders face intervening powers and domestic constituents with conflicting political priorities. Downes supports his arguments with statistical analyses of data he generates about 120 imposed regime changes between 1816 and 2008, as well as informed, engaging case studies. For the former, he might have been more discriminating in his selections of control variables. Optimal selections would exclude intervening variables and include only other factors non-spuriously related to both the principal explanatory and outcome variables.