This is a comprehensive contribution to an ongoing discussion of East Asia and the Pacific in an era of transformation. Earlier contributions by Gavan McCormack and Wada Haruki (on Northeast Asia), by David Rosenberg (on China and Southeast Asia), and by Lora Saalman (on the changing Chinese-Indian-U.S. strategic relationship) all raise issues posed by the rise of China as a major economic power in Asia and globally, and the repercussions of changing power relations reverberating throughout Asia. Noting that China remains a distant third to the U.S. and Japan in trade and investment in East and Southeast Asia, Economy highlights China’s rapid advance, above all in the realms of economics and finance, but also extending to a broad realms including governance, the resolution of territorial conflicts, the environment and others, with particular reference to Southeast Asia. At a time of rising China-Japan tensions, China appears to be making major multifaceted gains throughout Southeast Asia. This article also examines the possibilities of regional trajectories in which the U.S. role is sharply reduced.