What follows are summaries of research studies and papers investigating the impact and effectiveness of support groups and group psychotherapy across many domains. If you’d like an annotated bibliography with APA citations, you can find that here: Group Work, An Annotated Bibliography

Note: Some of the links you will find here and in the bibliography may not be accessible to you; I accessed them via my university library. If a link to a paper or text is inaccessible to you I encourage you to reach out to the authors via email. Or befriend a librarian, which is never a bad idea).

This is a living document – I’ll continue working on summaries of what I have read over time. Feel free to return!

Core texts and historical perspectives

Theory And Practice of Group Psychotherapy, Irwin Yalom & Molyn Leszcz.

First published in 1967, this has been a core text in the field for decades. It’s chunky, clocking in at over 700 pages, and is full of clinical vignettes, frameworks, and references to research.

Key insights:

  • There’s a central tension in groups – people who cannot or will not participate in the group task are unlikely to be helped by a group and may be harmed by it. BUT participants should be encouraged to stay because the issues we face inside a group are nearly inevitably the same challenges we face in the world. The group provides members the opportunity to face and master challenges in the ‘here and now’ of the group, thereby gaining skills that they can take into the real world to live better lives.

Yalom’s 11 therapeutic factors – the qualities present in a group that actually create change for participants – also remain widely cited today.

There’s so much more to this text, more than can fit in the kind of summaries I am presenting here; perhaps I’ll write a longer piece about it.

Developmental Sequence In Small Groups Bruce W. Tuckman, 1965, Psychological Bulletin.

In this paper, Tuckman outlines the group formation model that’s been widely referenced ever since, suggesting that groups go through the following phases:

  • Forming (putting a group together)
  • Storming (conflicts over who makes decisions, who gets heard)
  • Norming (developing group norms)
  • Performing (the group in its active work phase, can be indefinite)
  • Adjourning (wrapping up a group)

“The Status Of Psychiatric Inpatient Group Therapy: Past, Present And Future,” Emond & Rasmussen, 2012, Social Work With Groups.

The authors point out that early scientific literature showed clinicians seeking “curative treatment for mental illness” through the use of group psychotherapy, but that over time, clinicians retreated from “curative” to “therapeutic.” (It seems to me that many advances in medicine, including those areas relating to mental health, have been to make what were once fatal diseases into chronic but treatable ones).

Moving forward in time, we see the impact of managed care and cost controls: “This literature reveals three primary goals for inpatient group therapy: 1, to improve interpersonal skills, 2, to decrease symptoms, and 3, to expedite discharge.” This might not be as bad as it sounds, as ongoing research on psychiatric hospitalization indicates that for some patients it is actually destabilizing and increases the risk of suicide attempts. Getting and staying out of the hospital can be a valid goal. Note: this is a much longer paper, and worth reading for how changing theoretical perspectives over time influenced the practice of group therapy with patients, including how disproven theories (like the theory that schizophrenia was caused by emotionally cold mothers, leading to “reparenting” as a treatment approach) were abandoned in the light of new information.

Are support groups and group psychotherapy effective? Is group therapy as effective as 1:1 therapy?

Gary Burlingame of BYU is one of the major researchers in this area, carrying out large meta-analytic studies to find out whether or not group therapy has equivalent results to 1:1 therapy.

“Outcome Differences Between Individual And Group Formats When Identical and Nonidentical Treatments, Patients, and Doses Are Compared: A 25-Year Meta-Analytic Perspective,” Burlingame et al., 2016, American Psychological Association.

Systematic literature reviews are considered among the ‘gold standard’ evaluations for whether or not a treatment is effective. Burlingame and fellow researchers evaluated 67 studies comparing 1:1 therapy and group therapy and found that there was no difference in outcomes: “There were no differences between formats for rates of treatment acceptacne, dropout, remission and improvement.”

“Group therapy for mood disorders: A meta-analysis,” Janis, Burlingame et al., 2021, Psychotherapy Research.

A meta-analysis of 42 studies comparing group therapy to 1:1 therapy for mood disorders found “…Group therapy for depression produced superior outcomes compared to waitlist control and treatment as usual and equivalent outcomes to medication. Similarly, group therapy for bipolar disorder produced superior outcomes to treatment as usual.”

“Recent Developments in Group Psychotherapy Research“, Rosendahl, Burlingame et al, 2021, American Journal of Psychotherapy.

“Meta-analytic results demonstrate that group therapy is effective compared with nonactive treatment and is equivalent to other active treatments for various mental disorders.”

Are group modalities to support mental health underused? If so, why?

“Mental Health Care Equity and Access: A Group Therapy Solution“, Whittingham et al., 2023, American Psychologist

The authors estimate that increasing the availability of group therapy by 10% would increase treatment access for 3.5 million Americans, reduce the need for new clinicians by just under 35K, and save $5.6 billion.

So…why isn’t it used more? The authors offer several reasons but here’s one big one: money. “Individual therapy is significantly more expensive than group therapy, reimbursing the therapist at a higher rate. Center for Medicare and Medicaid Services [CMS] data suggest an average rate of approximately $152 for individual therapy compared to $27 for group therapy per person, whil also offering the therapist fewer logistical challenges.”

“Underutilization of short-term group therapy: Enigmatic or understandable?“ Piper, 2008, Psychotherapy Research

Piper notices that one of the most cited findings in all of psychotherapy research – the finding in Smith et al. (1980) that patient outcomes have less to do with the type of therapy being offered and more to do with the relationship between a client and clinician – is actually not based exclusively or even mostly on studies of 1:1 therapy. Almost half of that evidence comes from studies of group therapy.

This paper should be included on the basis of shade thrown alone: “Thus, the two primary conclusions of the Smith et al. review were to a large extent based on findings concerning short-term group therapy. However, it seemed as though the authors forgot to tell anyone, and nobody seemed to notice.”

Oh, he’s not done:

“The length of time that it took for the evidence to surface may also reflect the fact that clinicians usually do not read research publications. Finally, it may reflect much of the field’s ambivalence, even denial, of the efficacy of short-term group therapy.”

OWWWWW burn :fire emoji:

“Terrified Of Group Therapy: Investigating Obstacles To Entering Or Leading Groups,” Shay, 2021, American Journal of Psychotherapy.

Shay posits that both clients and clinicians fear groups for the same reason: fear of shame. Clients often come to therapy precisely to talk about issues that they have experienced shame around, and the idea of discussing those issues in a group rather than privately with a clinician may seem daunting. But it’s not just the clients who fear the group, says Shay: “…therapists may feel the powerful fear of being shamed or humiliated, unmasked in the eyes of many, not as a wizard, but as the person behind the curtain with a compelling voice but a lack of substance.”

“Group Psychotherapy As A Specialty: An Inconvenient Truth“ While group psychotherapy has been proven to be effective, and expanding it would expand access to treatment for millions, most programs that train mental health professionals do little or no training in group methodology, assuming that if a clinician can do 1:1 therapy, they can do groups. This isn’t true, and may be one of the reasons clinicians avoid establishing groups; either because they know at some level they are not prepared, or they try it and fail due to lack of preparation, and stop offering groups.

Are online groups as effective as in-person groups?

The evidence on differences between online and in person groups is mixed and still emerging. I summarize a few papers here. Links to come, I was typing on an airplane.

“Effectiveness of online mutual-help group attendance for adults with alcohol use disorders in the pooled, longitudinal US National PAL study cohorts,” Zemore, et al., 2025, Journal of Drug & Alcohol Dependence. The Recovery Bulletin summarized this study of 1,152 individuals with a diagnosis of alcohol use disorder who attended mutual-help groups. The study found that outcomes for attendees of in-person meetings were better at 6 months and 12 month followups. Furthermore, the study pointed out that higher levels of engagement and participation in in-person groups, along with the ability to form social connections with other sober people, were likely a factor in the differing outcomes between in-person and online groups.

A comparison of telehealth versus in-person group therapy: Results from a DBT-based dual diagnosis IOP,” Bean et. al, 2021, Journal of Clinical Psychology.

This study looked at outcomes for participants in an intensive outpatient program (IOP) offered for people who had both mental health and substance use disorder diagnoses. 96 participants engaged in the study, which found that outcomes for those who were enrolled in the IOP online and those in person had statistically equivalent outcomes.

Is Online Group Therapy As Effective as Face to Face Group Therapy? A Mixed Methods Study,” Lin et al., 2025, Clinical Social Work Journal

In this study of 214 participants, researchers found that online and face to face group therapy was equivalent across most domains except for cognitive domains. As a mixed methods study, one interesting feature of this paper is feedback from group participants on their impressions of what worked and what didn’t in each modality.

What about peer support groups?

“Alcoholics Anonymous and other 12-step programs for alcohol use disorder,” Kelly, et al., 2020, Cochrane Database of Systematic Reviews.

This 2020 systematic review of 67 studies involving more than 10,000 study participants made news at the time because it showed not only that 12-step facilitation programs and AA work, but that they work significantly better in helping people achieve abstinence than other treatments for alcohol use disorder, including cognitive behavioral therapy and motivational interviewing.

The Recovery Research Institute summarizes many important studies in their monthly newsletter, the Recovery Bulletin. That and much more can be found at their site, recoveryanswers.org.

What impact does group cohesion have, and what factors influence group cohesion?

Group cohesion - a sense of “we” is one of the 11 therapeutic factors that Yalom posits as the qualities in a group that help people heal and grow.

Cohesion in Group Therapy: A Meta-Analysis, Burlingame et al., 2018, Psychotherapy.

This meta-analysis found that across studies, there was a statistically significant correlation between group cohesion and treatment outcomes. The paper also discusses common definitions of cohesion and how it is measured.

Examining a Cohesion-Focused Model in Experiential Growth Groups: A Single Case Research Design, Zhu et al., 2023, Journal for Specialists In Group Work

In this study, researchers implemented a phased, cohesion-focused model across two experiential growth groups. The groups responded differently and the researchers examined potential causes.

Associations dedicated to studying group work and training group clinicians

Journals focused on publishing research in group work

You’ll note that many of the papers above were published in more generalist journals focused on psychiatry and psychology. There are, however, a few scientific journals that focus specifically on group work.

Other sites offering or summarizing research