The sample for this study was drawn from the UK700 Trial, a collaborative study involving four clinical centers and funded by grants from the UK Department of Health and the National Health Service Research and Development Programme. The authors thank Tom Butler, Ph.D., Francis Creed, F.R.C.Psych., Janelle Fraser, B.A., Nick Tarrier, Ph.D., and Theresa Tattan, Ph.D. (Manchester); Catherine Gilvarry, B.Sc., Kwame McKenzie, M.R.C.Psych., Robin Murray, D.Sc., Jim van Os, Ph.D., and Elizabeth Walsh, M.R.C.Psych. (King's School of Medicine and Maudsley Hospital, London); John Green, Ph.D., Anna Higgitt, M.R.C.Psych, Elizabeth van Horn, M.R.C.Psych, Donal Leddy, B.A., and Peter Tyrer, F.R.C.Psych (St. Mary's and St. Charles', London); Rob Bale, M.R.C. Psych., Andy Kent, M.D., and Chiara Samele, Ph.D. (St. George's Hospital, London); Sarah Byford, M.Sc., and David Torgerson, Ph.D. (Center for Health Economics, York); and Simon Thompson, D.Sc., and Ian White, Ph.D. (Statistical Centre, London).