From its earliest beginnings to its postcolonial afterlife, Japan's colonial rule of Taiwan proclaimed a commitment both to science and to modernity. During its fifty-one years of rule between 1895 and 1945, Japan developed Taiwan as a laboratory of empire. After the end of colonial rule, this scientific legacy became part of the "native" Taiwanese critique against the newly arrived Chinese Nationalist (Guomindang) regime. While Korea and other former colonies have denounced Japanese rule as brutal exploitation, contemporary Taiwanese have often embraced the colonial past as an integral part of their modern history. Why is Japanese colonialism remembered differently in Taiwan? What is the relationship between colonialism and modernity? How do the different legacies of Japanese colonialism affect the geopolitical configuration of East Asia today? I hope to shed light on these larger questions by exploring the social meanings of science in colonial and postcolonial Taiwan, from the end of the late Qing Dynasty to the present. For both Japanese and Taiwanese, science represented a sign of progress and modernity that served, at varying times, as an instrument of domination, a site of Pan-Asian solidarity, and a pathway to independence. My project traces these overlapping meanings of science in order to reinterpret received ideas of collaboration, nationalism, and identity formation that have shaped modern East Asia, and to suggest implications for the relationship between colonialism and postcolonialism around the globe.