We would like to thank those whose efforts made this report possible. Laura Chadwick, from the Office of the Assistant Secretary for Planning and Evaluation (ASPE), the current project officer for the study, and Susan Hauan, the former project officer for the study, have both provided invaluable guidance throughout the course of the study, as well as very helpful comments on both the substance and presentation of material in this report. We would also like to acknowledge the guidance of Julia Isaacs (now at the Brookings Institution) during the early phases of this project. At Mathematica Policy Research, Robert Wood carefully reviewed a draft of this report and provided very useful comments. Carol Razafindrakoto and Julie Sykes provided outstanding programming assistance in constructing the large and complex data files and in writing the computer programs to conduct the many analyses that were performed for this study. Finally, Jill Miller, Bill Garrett, and Jennifer Baskwell expertly produced the report, and Patricia Ciaccio and Leah Hackleman provided valuable editorial assistance. We gratefully acknowledge these contributions.