Background Maltreatment of older people (elder abuse) includes psychological, physical, sexual abuse, neglect and financial exploitation. Evidence suggests that 10% of older adults experience some form of abuse, and only a fraction of cases are actually reported or referred to social services agencies. Elder abuse is associated with significant morbidity and premature mortality. Numerous interventions have been implemented to address the issue of elder maltreatment. It is, however, unclear which interventions best serve to prevent or reduce elder abuse. Objectives The objective of this review was to assess the effectiveness of primary, secondary and tertiary intervention programmes used to reduce or prevent abuse of the elderly in their own home, in organisational or institutional and community settings. The secondary objective was to investigate whether intervention effects are modified by types of abuse, types of participants, setting of intervention, or the cognitive status of older people. Search methods We searched 19 databases (AgeLine, CINAHL, Psycinfo, MEDLINE, Embase, Proquest Central, Social Services Abstracts, ASSIA, Sociological Abstracts, ProQuest Dissertations & Theses Global, Web of Science, LILACS, EPPI, InfoBase, CENTRAL, HMIC, Opengrey and Zetoc) on 12 platforms, including multidisciplinary disciplines covering medical, health, social sciences, social services, legal, finance and education. We also browsed related organisational websites, contacted authors of relevant articles and checked reference lists. Searches of databases were conducted between 30 August 2015 and 16 March 2016 and were not restricted by language. Selection criteria We included randomised controlled trials (RCTs), cluster-randomised trials, and quasi-RCTs, before-and-after studies, and interrupted time series. Only studies with at least 12 weeks of follow-up investigating the effect of interventions in preventing or reducing abuse of elderly people and those who interact with the elderly were included. Data collection and analysis Two review authors independently extracted data and assessed the studies' risk of bias. Studies were categorised as: 1) education on elder abuse, 2) programmes to reduce factors influencing elder abuse, 3) specific policies for elder abuse, 4) legislation on elder abuse, 5) programmes to increase detection rate on elder abuse, 6) programmes targeted to victims of elder abuse, and 7) rehabilitation programmes for perpetrators of elder abuse. All studies were assessed for study methodology, intervention type, setting, targeted audience, intervention components and intervention intensity. Main results The search and selection process produced seven eligible studies which included a total of 1924 elderly participants and 740 other people. Four of the above seven categories of interventions were evaluated by included studies that varied in study design. Eligible studies of rehabilitation programmes, specific policies for elder abuse and legislation on elder abuse were not found. All included studies contained a control group, with five of the seven studies describing the method of allocation as randomised. We used the Cochrane 'Risk of bias' tool and EPOC assessment criteria to assess risk of bias. The results suggest that risk of bias across the included body of research was high, with at least 40% of the included studies judged as being at high risk of bias. Only one study was judged as having no domains at high risk of bias, with two studies having two of 11 domains at high risk. One study was judged as being at high risk of bias across eight of 11 domains. All included studies were set in high-income countries, as determined by the World Bank economic classification (USA four, Taiwan one, UK two). None of the studies provided specific information or analysis on equity considerations, including by socio-economic disadvantage, although one study was described as being set in a housing project. One study performed some form of cost-effectiveness analysis on the implementation of their intervention programmes, although there were few details on the components and analysis of the costing. We are uncertain whether these interventions reduce the occurrence or recurrence of elder abuse due to variation in settings, measures and effects reported in the included studies, some of which were very small and at a high risk of bias (low- and very low-quality evidence).Two studies measured the occurrence of elder abuse. A high risk of bias study found a difference in the post-test scores (P value 0.048 and 0.18). In a low risk of bias study there was no difference found (adjusted odds ratio (OR) =0.48, 95% 0.18 to 1.27) (n = 214). For interventions measuring abuse recurrence, one small study (n = 16) reported no difference in post-test means, whilst another found higher levels of abuse reported for the intervention arms (Cox regression, combined intervention hazard ratio (HR) = 1.78, alpha level = 0.01). It is uncertain whether targeted educational interventions improve the relevant knowledge of health professionals and caregivers (very low-quality evidence), although they may improve detection of resident-to-resident abuse. The concept of measuring improvement in detection or reporting as opposed to measuring the occurrence or recurrence of abuse is complicated. An intervention of public education and support services aimed at victims may also improve rates of reporting, however it is unclear whether this was due to an increase in abuse recurrence or better reporting of abuse.The effectiveness of service planning interventions at improving the assessment and documentation of related domains is uncertain. Unintended outcomes were not reported in the studies. Authors' conclusions There is inadequate trustworthy evidence to assess the effects of elder abuse interventions on occurrence or recurrence of abuse, although there is some evidence to suggest it may change the combined measure of anxiety and depression of caregivers. There is a need for high-quality trials, including from low- or middle-income countries, with adequate statistical power and appropriate study characteristics to determine whether specific intervention programmes, and which components of these programmes, are effective in preventing or reducing abuse episodes among the elderly. It is uncertain whether the use of educational interventions improves knowledge and attitude of caregivers, and whether such programmes also reduce occurrence of abuse, thus future research is warranted. In addition, all future research should include a component of cost-effectiveness analysis, implementation assessment and equity considerations of the specific interventions under review.