This paper tests the mobility transition theory using data from the October round of the monthly labor force surveys conducted in Taiwan in 1981-1985. The results suggest that migration in Taiwan in the first half of 1980's was basically in accord with what had been hypothesized by the theory for an industrialized society in terms of volume, direction and motivation of migration. When age and labor force status were controlled, the mobility transitional hypotheses were mostly supported by our data. Exceptions could be explained by greater rural industrialization and greater daily commuting than had been common in Western societies at a comparable stage of development.