Many workers retire abruptly from full-time employment, a pattern that standard life-cycle models with smooth preferences over leisure and consumption struggle to reconcile. This suggests that factors other than those governing preferences for labor supply – such as institutional and demand-side forces, including firms’ limited willingness to offer part-time work to older employees – play an important role. Distinguishing between these supply- and demand-side factors is challenging, as both shape observed labor supply behavior. We address this challenge by developing a new identification strategy that combines observational data with stated preferences for part-time work from strategic survey questions. Our preliminary results reveal that prime-aged men do not want to work part-time, exhibiting negative willingness to pay to reduce hours worked. However, their willingness to pay for part-time work becomes positive and sizable close to retirement age. In contrast, female reservation wages are sharply rising in hours worked, indicating that women do not want to work full-time. Viewed through the lens of our structural life-cycle model, these patterns are consistent with a large labor supply elasticity for women, and a slightly smaller elasticity for men.