"This important new book, written by renowned experts, takes a look under the bonnet of UN peacekeeping to examine how the different tasks peacekeepers are given interact with one another and influence the overall effectiveness of UN operations. Combining detailed case studies with rigorous social scientific analysis, this book takes a giant leap in thought and understanding. The results are so compelling that readers, academics, students, and practitioners alike, won't look at peacekeeping in the same way again." --Alex Bellamy, Professor of Peace and Conflict Studies, University of Queensland, Australia"Not always, but on average, peacekeeping works. This insightful book asks how and why peacekeeping is asked to work in ever more complex ways, with 'Christmas trees' of ambitions. Then it develops evidence-based principles for priority setting. 'Security first' is not a surprising finding. When a peace operation fails to stem the bloodshed and rape, subsequent goals, like moving on to a post-conflict election, likely will have limited success. A surprise, on the other hand, is that accomplishing 'democracy' with peace operation support is mostly not a gateway to further mission accomplishments. This is thoughtful, helpful research by greats of peacekeeping research on matters of importance." --John Braithwaite, Distinguished Emeritus Professor, Australian National University"Diehl, Druckman and Mueller add a valuable perspective on our understanding of peace operations success (and failure) by focusing on a neglected factor: missions' interdependencies. The book offers novel insights on how to define and assess compatibility between simultaneous or sequential missions, and implications for success. The conceptualization and operationalization of compatibility is followed by a clear set of empirical expectations tested across five in-depth case studies, which include some of the most prominent peacekeeping missions...Academic rigor and policy relevance makes the book a must-read for those interested in the study and practice of peace operations." --Jessica Di Salvatore, Associate Professor in Political Science and Peace Studies, University of Warwick"Peacekeeping operations are tasked with many 'missions,' some of which overlap, are contradictory, or have varying effects on one another. The authors build a novel quantitative dataset, while employing qualitative cases studies, in order to evaluate the extent to which one mission, say, promoting democratic elections, might reinforce or undermine other missions like providing security. In this way, the authors fill an important 'middle-level' theoretical and empirical gap in the literature. A must-read for peacekeeping scholars, students, and practitioners." --Lise Howard, Professor of Government and Foreign Service, Georgetown University, and President of the Academic Council on the United Nations System