Introduction: Quantification of the social climate of mental health care environments has received considerable attention. Investigations of the resulting measures indicate that social climate is associated with individual outcomes including patient satisfaction and staff burnout. Interest has grown in developing interventions to improve social climate in anticipation of subsequent related benefits. This study aimed to identify and critically review research about the effectiveness of interventions for improving social climate in inpatient adult acute mental health settings. Methods: Systematic review reported in line with the Preferred Reporting Items for Systematic reviews and Meta-Analyses. Comprehensive terms were used to search multiple electronic databases from inception to July 2019. Information about intervention type(s), complexity was extracted and study quality was assessed. Results: Twenty-three papers met inclusion criteria of which 20 used a pretest–posttest study design and three employed randomized and/or controlled designs. Interventions were environmental/structural, operational/process-oriented and developmental/person-oriented in nature and they ranged in complexity. The Ward Atmosphere Scale was the most common outcome measure used. Following quality assessment, six studies were judged to be sufficiently robust in terms of quality, theory-base, user-inclusion, and outcomes evaluation to contribute credibly to the evidence base. Of these, four complex person- and process-oriented intervention studies and two less complex structural/environmental intervention studies resulted in positive outcomes. Conclusion: There is limited strong evidence that interventions positively influence measures of ward social climate in acute adult mental health settings. Such measures should not be the sole criterion of success when evaluating change. Decisions about implementing change to improve social climate should be informed by meaningful proxy measures including the views and preferences of service users and other stakeholders. Studies using stronger designs are required to establish the ability of interventions to improve social climate.