We analyze the forces that can generate retirement in different versions of standard life cycle models of labor supply. While nonconvexities in production can generate retirement, we show that the size of nonconvexities needed increases sharply as the intertemporal elasticity of substitution for labor decreases. In a model with home production, we show that these models imply a large increase in time devoted to home production at retirement. This is contrary to what is found in the ATUS data. We suggest that nonconvexities in the enjoyment of leisure time may be a promising alternative feature to generate retirement.