The effort to improve state institutions in postconflict societies is a complicated business. Even when foreign intervention is carried out with the best of intentions and the greatest resources it often fails. What can account for this failure In Institution Building in Weak States Andrew Radin argues that the international communitys approach to building state institutions needs its own reform. This innovative book proposes a new strategy rooted in a rigorous analysis of recent missions.In contrast to the common strategy of foreign intervenersimposing models drawn from Western countriesRadin shows how pursuing incremental change that accommodates local political interests is more likely to produce effective accountable and lawabiding institutions. Drawing on extensive field research and original interviews Radin examines efforts to reform the central government military and police in postconflict Bosnia and Herzegovina Kosovo Iraq and TimorLeste. Based on his own experience in defense reform in Ukraine after 2014 Radin also draws parallels with efforts to improve state institutions outside of postconflict societies.Institution Building in Weak States introduces a domestic opposition theory that better explains why institution building fails and what is required to make it work. With actionable recommendations for smarter policy the book offers an important corrective for scholars and practitioners of postconflict missions international development peacebuilding and security cooperation.