BACKGROUND: Being diagnosed with human immunodeficiency virus (HIV), and labelled with a chronic, life-threatening, and often stigmatizing disease, can impact on a person's well-being. Psychosocial group interventions aim to improve life-functioning and coping as individuals adjust to the diagnosis. OBJECTIVES: To examine the effectiveness of psychosocial group interventions for improving the psychological well-being of adults living with HIV/AIDS. SEARCH METHODS: We searched the following electronic databases up to 14 March 2016: the Cochrane Central Register of Controlled Trials (CENTRAL) published in the Cochrane Library (Issue 2, 2016), PubMed (MEDLINE) (1996 to 14 March 2016), Embase (1996 to 14 March 2016), and Clinical Trials.gov. SELECTION CRITERIA: Randomized controlled trials (RCTs) or quasi-RCTs that compared psychosocial group interventions with versus control (standard care or brief educational interventions), with at least three months follow-up post-intervention. We included trials that reported measures of depression, anxiety, stress, or coping using standardized scales. DATA COLLECTION AND ANALYSIS: Two review authors independently screened abstracts, applied the inclusion criteria, and extracted data. We compared continuous outcomes using mean differences (MD) with 95% confidence intervals (95% CIs), and pooled data using a random-effects model. When the included trials used different measurement scales, we pooled data using standardized mean difference (SMD) values. We reported trials that we could not include in the meta analysis narratively in the text. We assessed the certainty of the evidence using the GRADE approach. MAIN RESULTS: We included 16 trials (19 articles) that enrolled 2520 adults living with HIV. All the interventions were multifaceted and included a mix of psychotherapy, relaxation, group support, and education. The included trials were conducted in the USA (12 trials), Canada (one trial), Switzerland (one trial), Uganda (one trial), and South Africa (one trial), and published between 1996 and 2016. Ten trials recruited men and women, four trials recruited homosexual men, and two trials recruited women only. Interventions were conducted with groups of four to 15 people, for 90 to 135 minutes, every week for up to 12 weeks. All interventions were conducted face-to-face except two, which were delivered by telephone. All were delivered by graduate or postgraduate trained health, psychology, or social care professionals except one that used a lay community health worker and two that used trained mindfulness practitioners.Group-based psychosocial interventions based on cognitive behavioural therapy (CBT) may have a small effect on measures of depression, and this effect may last for up to 15 months after participation in the group sessions (SMD -0.26, 95% CI -0.42 to -0.10; 1139 participants, 10 trials, low certainty evidence). Most trials used the Beck Depression Inventory (BDI), which has a maximum score of 63, and the mean score in the intervention groups was around 1.4 points lower at the end of follow-up. This small benefit was consistent across five trials where participants had a mean depression score in the normal range at baseline, but trials where the mean score was in the depression range at baseline effects were less consistent. Fewer trials reported measures of anxiety, where there may be little or no effect (four trials, 471 participants, low certainty evidence), stress, where there may be little or no effect (five trials, 507 participants, low certainty evidence), and coping (five trials, 697 participants, low certainty evidence).Group-based interventions based on mindfulness have not demonstrated effects on measures of depression (SMD -0.23, 95% CI -0.49 to 0.03; 233 participants, 2 trials, very low certainty evidence), anxiety (SMD -0.16, 95% CI -0.47 to 0.15; 62 participants, 2 trials, very low certainty evidence), or stress (MD -2.02, 95% CI -4.23 to 0.19; 137 participants, 2 trials, very low certainty evidence). No mindfulness based interventions included in the studies had any valid measurements of coping. AUTHORS' CONCLUSIONS: Group-based psychosocial interventions may have a small effect on measures of depression, but the clinical importance of this is unclear. More high quality evidence is needed to assess whether group psychosocial intervention improve psychological well-being in HIV positive adults.