Japanese economic development and Japanese American economic achievements suggest that these groups can provide tests of the Weberian thesis. The immigrant generation of Japanese Americans is studied using JARP data and multiple regression. Several indicators of traditional religious involvement have independent effects on self-employment and income attainment. Religious variables predict economic achievement more constantly than family background or education for these data. The Japanese Americans' institutional context influenced their occupational opportunities and choices. Japanese religion provided ethical motivations for en-trepreneurship. These research findings suggest the importance of religious ethics for economic behavior.