Background: Self-harm (SH; intentional self-poisoning or self-injury) is common, often repeated, and associated with suicide. This is an update of a broader Cochrane review first published in 1998, previously updated in 1999, and now split into three separate reviews. This review focuses on psychosocial interventions in adults who engage in self-harm. Objectives: To assess the effects of specific psychosocial treatments versus treatment as usual, enhanced usual care or other forms of psychological therapy, in adults following SH. Search methods: The Cochrane Depression, Anxiety and Neurosis Group (CCDAN) trials coordinator searched the CCDAN Clinical Trials Register (to 29 April 2015). This register includes relevant randomised controlled trials (RCTs) from: the Cochrane Library (all years), MEDLINE (1950 to date), EMBASE (1974 to date), and PsycINFO (1967 to date). Selection criteria: We included RCTs comparing psychosocial treatments with treatment as usual (TAU), enhanced usual care (EUC) or alternative treatments in adults with a recent (within six months) episode of SH resulting in presentation to clinical services. Data collection and analysis: We used Cochrane's standard methodological procedures. Main results: We included 55 trials, with a total of 17,699 participants. Eighteen trials investigated cognitive-behavioural-based psychotherapy (CBT-based psychotherapy; comprising cognitive-behavioural, problem-solving therapy or both). Nine investigated interventions for multiple repetition of SH/probable personality disorder, comprising emotion-regulation group-based psychotherapy, mentalisation, and dialectical behaviour therapy (DBT). Four investigated case management, and 11 examined remote contact interventions (postcards, emergency cards, telephone contact). Most other interventions were evaluated in only single small trials of moderate to very low quality. There was a significant treatment effect for CBT-based psychotherapy compared to TAU at final follow-up in terms of fewer participants repeating SH (odds ratio (OR) 0.70, 95% confidence interval (CI) 0.55 to 0.88; number of studies k = 17; N = 2665; GRADE: low quality evidence), but with no reduction in frequency of SH (mean difference (MD) -0.21, 95% CI -0.68 to 0.26; k = 6; N = 594; GRADE: low quality). For interventions typically delivered to individuals with a history of multiple episodes of SH/probable personality disorder, group-based emotion-regulation psychotherapy and mentalisation were associated with significantly reduced repetition when compared to TAU: group-based emotion-regulation psychotherapy (OR 0.34, 95% CI 0.13 to 0.88; k = 2; N = 83; GRADE: low quality), mentalisation (OR 0.35, 95% CI 0.17 to 0.73; k = 1; N = 134; GRADE: moderate quality). Compared with TAU, dialectical behaviour therapy (DBT) showed a significant reduction in frequency of SH at final follow-up (MD -18.82, 95% CI -36.68 to -0.95; k = 3; N = 292; GRADE: low quality) but not in the proportion of individuals repeating SH (OR 0.57, 95% CI 0.21 to 1.59, k = 3; N = 247; GRADE: low quality). Compared with an alternative form of psychological therapy, DBT-oriented therapy was also associated with a significant treatment effect for repetition of SH at final follow-up (OR 0.05, 95% CI 0.00 to 0.49; k = 1; N = 24; GRADE: low quality). However, neither DBT vs 'treatment by expert' (OR 1.18, 95% CI 0.35 to 3.95; k = 1; N = 97; GRADE: very low quality) nor prolonged exposure DBT vs standard exposure DBT (OR 0.67, 95% CI 0.08 to 5.68; k = 1; N =18; GRADE: low quality) were associated with a significant reduction in repetition of SH. Case management was not associated with a significant reduction in repetition of SH at post intervention compared to either TAU or enhanced usual care (OR 0.78, 95% CI 0.47 to 1.30; k = 4; N = 1608; GRADE: moderate quality). Continuity of care by the same therapist vs a different therapist was also not associated with a significant treatment effect for repetition (OR 0.28, 95% CI 0.07 to 1.10; k = 1; N = 136; GRADE: very low quality). None of the following remote contact interventions were associated with fewer participants repeating SH compared with TAU: adherence enhancement (OR 0.57, 95% CI 0.32 to 1.02; k = 1; N = 391; GRADE: low quality), mixed multimodal interventions (comprising psychological therapy and remote contact-based interventions) (OR 0.98, 95% CI 0.68 to 1.43; k = 1 study; N = 684; GRADE: low quality), including a culturally adapted form of this intervention (OR 0.83, 95% CI 0.44 to 1.55; k = 1; N = 167; GRADE: low quality), postcards (OR 0.87, 95% CI 0.62 to 1.23; k = 4; N = 3277; GRADE: very low quality), emergency cards (OR 0.82, 95% CI 0.31 to 2.14; k = 2; N = 1039; GRADE: low quality), general practitioner's letter (OR 1.15, 95% CI 0.93 to 1.44; k = 1; N = 1932; GRADE: moderate quality), telephone contact (OR 0.74, 95% CI 0.42 to 1.32; k = 3; N = 840; GRADE: very low quality), and mobile telephone-based psychological therapy (OR not estimable due to zero cell counts; GRADE: low quality). None of the following mixed interventions were associated with reduced repetition of SH compared to either alternative forms of psychological therapy: interpersonal problem-solving skills training, behaviour therapy, home-based problem-solving therapy, long-term psychotherapy; or to TAU: provision of information and support, treatment for alcohol misuse, intensive inpatient and community treatment, general hospital admission, or intensive outpatient treatment. We had only limited evidence on whether the intervention had different effects in men and women. Data on adverse effects, other than planned outcomes relating to suicidal behaviour, were not reported. Authors' conclusions: CBT-based psychological therapy can result in fewer individuals repeating SH; however, the quality of this evidence, assessed using GRADE criteria, ranged between moderate and low. Dialectical behaviour therapy for people with multiple episodes of SH/probable personality disorder may lead to a reduction in frequency of SH, but this finding is based on low quality evidence. Case management and remote contact interventions did not appear to have any benefits in terms of reducing repetition of SH. Other therapeutic approaches were mostly evaluated in single trials of moderate to very low quality such that the evidence relating to these interventions is inconclusive.