This book investigates whether a power shift has taken place in the Asia-Pacific region since the end of the Cold War. By systematically examining the development of power dynamics in Asia-Pacific, it challenges the notion that a wealthier and militarily more powerful China is automatically turning the regional tides in its favour. With a special emphasis on Sino-US competition, the book explores the alleged linkage between the regional distribution of relevant material and immaterial capabilities, national power and the much-cited regional power shift. The book presents a novel concept for measuring power in international relations by outlining a composite index on aggregated power (CIAP) that includes 55 variables for 44 regional countries and covers a period of twenty years. Moreover, it develops a middle power theory that outlines the significance of middle powers in times of major power shifts. By addressing political, military and economic cooperation via a structured-focused comparison and by applying a comparative-historical analysis, the book analyses in depth the bilateral relations of six regional middle powers to Washington and Beijing.