Informal caregiving, or the provision of unpaid, voluntary care to elderly or disabled family and friends, is an increasingly common experience for both men and women in late midlife. The authors examine the ways in which informal caregiving influences the transition to retirement and how this relationship is shaped by gender. Our data are 763 pension-eligible men and women in the 1994-1995 Cornell Retirement and Well-Being Study. Results from discrete-time event history analyses indicate that certain types of caregiving shape the timing of retirement but that the association depends on the relationship between caregiver and care recipient and is fundamentally moderated by gender. For example, wives caring for their husbands have retirement odds 5 times greater than women who are not caregivers, whereas husbands caring for their wives are substantially slower to retire. Our evidence suggests that in this sample, caregiving responsibilities lead to increased sex role-typical employment behavior in late midlife.