In his Commentary, Dr Kendler makes a series of thoughtful points about our article and the state of the science in the analysis of gene × environment effects. He suggests that our analysis would be enhanced by a more comprehensive assessment of interns' work conditions at baseline and an exploration of factors that could predict differential trajectories of depression during internship. We appreciate these suggestions and plan to incorporate them in analyses of this growing data set that includes additional time points conducive to growth modeling. Dr Kendler also called attention to the fact that we found an association between depression and long work hours, which differs from prior reports. Although, as he points out, varying perceptions of working conditions may play a role in this difference, our sample was substantially larger than those in previous studies. Consequently, insufficient statistical power may explain the failure of previous studies to identify work hours as a correlate of depression.