This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book examines a comparative analytical method and the lens of readiness theory to study the dynamics of conflict resolution in these hard cases, with the aim of drawing lessons for a broader investigation of the conditions and processes that contribute to the success or failure of peace negotiations in intractable conflicts. It addresses both the pre-negotiation and the negotiation stages in several case studies. The book provides an overview of the literature on intractable conflicts and their characteristics and then presents the two theoretical strands for understanding de-escalation processes in political conflicts: ripeness strand and readiness strand. It discusses the factors that led to peace agreements in the conflicts in Aceh and Sudan. The book describes the utility of readiness theory in explaining the successes and failures of the cases studied and outlines some future directions for research on readiness theory.