Puerto Rico experienced rapid economic growth between 1950 and 1980. The authors find empirical support for the thesis that such growth leads first to a decline in women's labor force activity, followed by an increase. On the other hand, men's level of labor force activity declined steadily over this period. The industrial and occupational nature of labor force activity changed dramatically for both sexes, corresponding to shifts in economic policy. Detailed occupational data from the decennial censuses are used to demonstrate that occupational sex segregation declined steadily between 1950 and 1980, even though a large proportion of women remained clustered in relatively few occupations. The gap between men's and women's earnings narrowed substantially after 1949; indeed, women's median earnings exceeded those of men in 1959 and remained near parity thereafter. -Authors