“…Indeed, the length of follow-up in treatment outcome studies varies from several weeks to several years (see reviews by Ivanoff & Stem, 1992;Nicholson & Berman, 1983;Smith, Glass, & Miller, 1980). For problems which have a chronic and cyclical course with periods of relapse and recovery, such as substance abuse, longer follow-up periods are necessary (Brown, Vik, & Creamer, 1989;Farrington, 1992;Green & Hergert, 1989;Kazdin, 1987;Milkman, Weiner, & Sunderwith, 1984;Vaillant & Milofsky, 1982;Watson & Purcell, 1985). Consequently, some have argued that drug and alcohol abuse treatment outcome studies should include follow-up assessments at least 1 year after termination (Davidge & Forman, 1988;Lambert, Shapiro, & Bergin, 1986;O'Farrell, 1992).…”