This paper examines the secular increase in the labor market activity of married women in the United States from 1975 to 1991. The research stresses two findings consistent with the hypothesis that married women increased their attachment to the labor force during this time period. First, increasing duration, not incidence, of married women's employment spells contributes the most to the increase in their rate of employment from 1975 to 1991. Second, the increase in married women's employment over the 1980s is largely due to their increased willingness to work more at any given wage, not their rising wage opportunities. (JEL J22, J31, J64)