Previous editions of Peace and Conflict reported evidence of a sustained post-Cold War decline in armed conflicts within states and a growing capacity of states, acting singly and multilaterally, to avoid and end internal wars. This volume has no such clear story line. New evidence, and a closer look at old evidence, suggests that if there was a global movement toward peace in the 1990s and early years of the 21st century, it has stalled. Some positive trends are still evident but they are offset by new challenges. These challenges point to a conflict syndrome—a collection of factors that often operate concurrently to undermine the stability of states and erode the foundations of human security. Taken together, the essays in this volume explore aspects of these factors.