Yanihara Tadao was a well-known Christian and pacifist who occupied the Chair of Colonial Policy at Tokyo Imperial University from 1923-1937. His extensive commentary on Japanese as well as European colonial policy is remarkable not only for its scholarly integrity but also for its breadth, and represents a comprehensive body of writing in Japanese before World War II. This historically contextualized analysis of Yanihara's commentary on Japanese colonial policy offers both an intellectual biography and an analysis of his theories of colonization and imperialism and his empirical studies of conditions in the Japanese colonies based on his own observations. It contains a critical analysis of Japanese colonial policy in Taiwan, Korea, Micronesia, Manchuria and China which is placed within the historical conditions prevailing in 1920s and 1930s Japan. The final chapter charts Yanihara's downfall during the notorious Yanihara Incident of 1937 where a clash with university authorities and ultimately the public prosecutor led to his enforced resignation and the banning of many of his books.