title “Can Constant Treatment Effects Within Subgroup Explain Heterogeneity in Welfare Reform Effects? ” The

data used in this paper are derived from data files made available to researchers by MDRC. The authors remain solely responsible for how the data have been used or interpreted. We are very grateful to MDRC for providing the public access to the experimental data used here. We would also like to thank Joe Altonji, Richard Blundell, Mike Boozer