The five-fold increase in the labor force participation rate of married women over the last half century was not accompanied by a substantial increase in the average job market experience of working women. Two data sets giving life-cycle labor force histories for cohorts of women born from the 1880s to 1910s indicate substantial (unconditional) heterogeneity in labor force participation. Married women in the labor force had a high degree of attachment to it; increased participation rates brought in women with little prior job experience and reduced cumulated years experience. According to extant schedules froma 1939 Women's Bureau Bulletin, 86% of married women born around 1895 and working in 1939 had been employed 50% of the years since beginning work, and 47% had worked 88% of those years. Average years of experience for cross sections of working married women hardly increased from 1920 to 1950, rising from 9 to 10.5 years. Because wages are calculated only for currently employed individuals, the steadiness in relative wages of women to men over this period may result from stable experience ratings for employed married women. An exploration of the determinants of labor force persistence points to the importance of occupational choice early in the work history of a woman and to the rise in clerical and professional occupations in extending life-cycle labor force participation.