This edited volume focuses on the changing regional security dynamics of Southeast Asia within the context of the U.S.-China strategic competition in the Indo-Pacific. On the one hand, China's growing influence and assertive behavior in the South China Sea and the Archipelago region are the main concerns of these countries. On the other hand, Southeast Asian countries are skeptical-if not hesitant-with the formation of new mini-lateral frameworks and emerging institutional cooperation such as the Quadrilateral Security Dialogue (Quad) and AUKUS. In this highly competitive strategic environment, these countries prefer to position themselves in a flexible mode of sometimes leaning toward the United States or China based on a nuanced balance of maintaining both strategic autonomy and opportunities that manifest in the region. In line with this flexible mode of engagement, Southeast Asian countries prefer to eschew an explicitly pro-position vis-a-vis the United States or China, cognizant of the turbulence ahead due to the deepening of U.S.-China strategic competition-this, despite the fact that freedom of navigation and a rule-based international order is much desired by Southeast Asian countries to establish and maintain peace and stability in the region. The strategic value of Southeast Asia has much significance to the deepening U.S.-China strategic competition. In this book, chapters examine the behavior, perspectives, and strategy of Southeast Asian countries toward the U.S.-China strategic competition in the Indo-Pacific. This book is aimed at scholars, strategists, policy makers, and students in the field of international relations and international security studies.