This study investigated the effectiveness of support groups for people living with chronic ill-health conditions. Searches of the published literature were undertaken for the period 1993–2013. Papers were included if participants were between 18 and 65 years old, and study designs were either pre-test post-test one group descriptive, non-randomised group comparison, or randomised controlled trial, with reported data appropriate for meta-analysis and sufficient for estimating effect size(s). Total 19 studies were eligible in the meta-analysis, and 2,986 participants were examined. Six general outcome categories emerged from the data: (1) psychosocial functioning, (2) self-efficacy, (3) quality of life, (4) health status, (5) health behaviours and (6) health care use. In total, 155 effect sizes were calculated from the outcome measures with 15.5% resulting in a large effect size, 6% moderate effects, 39% small effects, and 39.5% producing trivial effects. The majority of the effect sizes (92%) were in the hypothesised direction. Overall, results demonstrate that self-help and support group interventions can positively influence management of chronic ill-health conditions and contribute to the desired outcome of successful adaptation.