The joint effort by the U.S. government and the political elite of Puerto Rico to industrialize the island created increased demand for female labor and a decline in the number of jobs traditionally held by men. The authors examine whether women's labor force participation in the formal sector responds to improving opportunities for women, declining opportunities for men, or the household's changing opportunity structures. Specifically, they examine a woman's return to work after the birth of her first child as the (...) initial point of conflict between productive and reproductive work. The data used in these analyses are from the 1982 Puerto Rican Fertility and Family Planning Assessment, an islandwide, representative sample of never-married and ever-married women between the ages of fifteen and forty-nine. The authors estimate a series of nested logistic regression models to evaluate the influence of occupational expansion or contraction on the timing of return to work after the first birth. Their findings offer selective support for the idea that women's lives are affected primarily by the occurrence of growing labor demand for women's labor. (shrink)