Background: This study adds to the limited evidence concerning the benefits of Interpersonal Psychotherapy (IPT) with depressed adolescents. It evaluates the long-term effects of group versus individual delivery of this treatment approach. Aims: To conduct a small-scale examination of the long-term efficacy of group versus individual delivery of IPT for depressed adolescents. Method: Thirty-nine adolescents, aged 13-19 years, with a primary diagnosis of Major Depressive Disorder, were randomly assigned in blocks to either group or individual delivery of IPT. Standardized clinical interview and questionnaire assessments were conducted at pre- and posttreatment, and 12-month follow-up. Results: Intent-to-treat (ITT) analyses indicated significant improvements in depression, anxiety, youth-reported internalizing problems, and global functioning from pre- to posttreatment for those receiving IPT, with no significant differences in outcome between group and individual formats of delivery. Improvements were maintained at 12-month follow-up. Completer analyses also revealed significant and sustained improvements on these measures for those receiving IPT, with no differences in outcome between therapy formats for most measures. Individual IPT showed significantly greater improvements than group IPT in parent-reported internalizing problems for the completer but not the ITT analyses. Conclusions: Both individual and group formats of IPT offer promise in producing long-term benefits in the treatment of depression among adolescents.