The continuing development and refinement of empirically supported interventions to increase participation in posttreatment care and promote sustained abstinence from illicit drug use is a priority for the addictions field. The purpose of this study was to assess the combined and relative effectiveness of four types of counseling styles, delivered by telephone, relative to a no call control condition. Stimulant users (N = 302) were randomized to one of four low-cost, telephone support protocols (unstructured/nondirective, unstructured/directive, structured/nondirective, structured/directive) or a standard referral to aftercare without telephone counseling (control). All of the study participants were nearing the completion of (or had completed) an intensive phase of structured, outpatient stimulant abuse treatment. Drug use and aftercare participation were assessed at 3 and 12 months following randomization. Intent-to-treat analyses showed no significant time-by-group interactions for these primary outcomes. Subsequent analyses, however, revealed a significant difference between the aggregated call groups and the control group at the time of the 3-month follow-up. The mean ASI drug use severity composite score for subjects in the call conditions declining from .058 at baseline to .048 at 3 months, whereas the no call/control group average score increased from .053 to .062 (χ (1) = 4.95, p = .026). A similar—and slightly stronger—effect was found when the study sample was restricted to those reporting any use during the month prior to the baseline interview (n = 152). This study provides modest support for the telephone-based counseling approaches strategies examined in this project. Subsequent research will assess interactions between patient characteristics and counseling styles, and improved identification of which treatment graduates might be more likely to benefit from this type of continuing support.