Factor Structure and Validity of the Therapeutic Factors Inventory–Short Form Anthony S. Joyce University of Alberta Rebecca MacNair-Semands The University of North Carolina at Charlotte Giorgio A. Tasca The Ottawa Hospital, Ottawa, Ontario, Canada; The University of Ottawa John S. Ogrodniczuk University of British Columbia Clinical group practice is commonly guided by the assumption that 11 distinct therapeutic factors operate in psychotherapy groups. This assumption should be closely examined due to the emerging evidence of fewer, more global therapeutic factors. The present study was conducted to continue the development of the Therapeutic Factors Inventory–Short Form (TFI–S) and focused on confirming its factor structure and evaluating aspects of its concurrent, discriminant, and predictive validity. A sample comprising a total of 435 clients from 52 distinct therapy groups at eight different clinical sites in the U.S. and Canada was obtained. Structural equation modeling analyses indicated that a four- factor model had a reasonably good fit to the TFI–S rating data, and it provided indications for further refinement of the constituent items. The analyses resulted in a revised, 19-item measure, the Therapeutic Factors Inventory–19 (TFI–19). Three-level HLM analyses demonstrated that the four factors were sensitive to change in member perceptions over time. Significant and meaningful relationships between the TFI–19 factors and subscales of the Group Climate Questionnaire-Short Form provided support for the concurrent validity of the TFI–19. Two-level HLM analyses identified signif- icant relationships between the TFI–19 factors and posttreatment status on symptomatic and interpersonal distress, thereby supporting the predictive validity of the TFI–19. The findings suggest that the TFI–19 may be a useful instrument to assess group members’ perceptions of more global therapeutic factors. Keywords: therapeutic factors, group psychotherapy, assessment Group therapy is a powerful therapeutic agent for helping people with a wide range of health and mental health problems (Burlingame, MacKenzie, & Strauss, 2004; McRoberts, Bur- lingame, & Hoag, 1998). However, the mecha- nisms through which group therapy achieves its effects are less understood. Clinical observation and previous research have suggested several promising areas for understanding how group therapy works. One such area concerns the ther- apeutic factors (Yalom, 1995) that are operative in clinical therapy groups. Therapeutic factors (TFs) have a rich history in the group literature and have been described This article was published Online First August 8, 2011. Anthony S. Joyce, Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada; Rebecca MacNair- Semands, Counseling Center, The University of North Caro- lina at Charlotte; Giorgio A. Tasca, Department of Psychology, The Ottawa Hospital, and Department of Psychiatry, The Uni- versity of Ottawa, Ottawa, Ontario, Canada; John S. Ogrod- niczuk, the Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada. This research was supported by a grant awarded by the Group Psychotherapy Foundation of the American Group Psychotherapy Association. Some of the data for this study were also collected as part of a grant awarded by the Canadian Institutes for Health Research, Institute of Gender and Health. Special appreciation to Kristi Vera, Linda God- dard, Theo DeGagne, Ward Nicholson, and Amanda Shep- tycki for their contributions to this article. Correspondence concerning this article should be ad- dressed to Rebecca MacNair-Semands, Counseling Center, 158 Atkins, The University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223-0001. E-mail: RRMACNAI@uncc.edu Group Dynamics: Theory, Research, and Practice © 2011 American Psychological Association 2011, Vol. 15, No. 3, 201–219 1089-2699/11/$12.00 DOI: 10.1037/a0024677 201