Presenting fresh insights on the internal dynamics and global contexts that shaped foreign relations in early modern Japan, Robert I. Hellyer challenges the still largely accepted wisdom that the Tokugawa shogunate, guided by an ideology of seclusion, stifled intercourse with the outside world, especially in the eighteenth and nineteenth centuries. Examining diplomacy, coastal defense, and foreign trade, this study demonstrates that while the shogunate created the broader framework, foreign relations were actually implemented through cooperative but sometimes competitive relationships with the Satsuma and Tsushima domains, which themselves held largely independent ties with neighboring states. Successive Tokugawa leaders also proactively revised foreign trade, especially with China, taking steps that mirrored the commercial stances of other Asian and Western states. In the nineteenth century, the system of foreign relations continued to evolve, with Satsuma gaining a greater share of foreign trade and Tsushima assuming more responsibility in coastal defense. The two domains subsequently played key roles in Japan’s transition from using early modern East Asian practices of foreign relations to the national adoption of international relations, especially the recasting of foreign trade and the centralization of foreign relations authority, in the years surrounding the Meiji Restoration of 1868.