This book investigates the reasons why regional integration in East Asia has been much weaker than in other parts of the world. It focuses particularly on economic factors, examining the economies of the different countries in the region, the linkages between them and between other parts of the world, and the economic sectors which are strong in East Asia. It concludes that the economic factors which make for strong regional integration are not prevalent in East Asia, with each national economy having specific sectoral focuses and priorities for their individual economies which in turn determine the extent to which each country engages with regional institutions such as the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP) or the Regional Comprehensive Economic Partnership (RCEP). The book argues that these economic factors which are specific to each national economy override other factors which might make for regional integration, such as political choices or the strength of the regional institutions.