This study drew on a life course approach and a sample of 293 women from four birth cohorts in upstate New York to examine the relationship over time between women's paid work and their informal caregiving of aging or infirm relatives. We find that such caregiving is an increasingly likely role for women, both as they age and across birth cohorts. One in four (24%) women became caregivers at some time between ages 35-44, and over one in three (36%) of these same women became caregivers between ages 55-64. Only 45 percent of the oldest cohort (born 1905-1917) were ever caregivers, compared to 64 percent of the most recent cohort (born 1927-1934), an increase of almost 20 percent. Clearly changes in the labor force participation of more recent cohorts of women do not appear to alter their caregiving responsibilities. In fact, women in this sample were equally likely to become caregivers, regardless of whether or not they were employed.