Non-state policing emerges in situations where formal police agencies are unable to fulfil their roles, either because: they lack resources and capacity; they are corrupt and/or carry out human rights abuses; there are conflict and instability; people find it difficult to access formal security and justice mechanisms. Non-state policing providers are generally more accessible to citizens, have greater popular legitimacy, and are more responsive to local demands, as well as more accountable. There are also risks, though, notably of lack of representation (e.g. women, minorities) and of human rights abuses. Examples of non-state policing are to be found in many developing countries, particularly Africa. These vary hugely in nature, functioning and impact – both positive (reducing crime) and negative (e.g. human rights abuses). State responses to non-state policing providers also vary from hostility to collaboration. Northern Ireland and the former Soviet Union/Eastern European countries do have some non-state actors involved in security functions, but they are better categorised as examples of formal police reform (as in of formal police agencies) in response to vastly changed circumstances and the challenges faced in this. This review looks at more palpable examples of non-state policing: Policia Communitaria in Mexico, vigilante groups in Nigeria, diverse non-state policing providers in Papua New Guinea, rondas campesinas in Peru, and sungusungu committees in Tanzania. While community policing (as in involving formal police agencies) has been widely studied, this review found far less literature on non-state policing. The bulk was academic papers. The literature clearly points to a lack of representation of women in non-state policing providers; there is also some reference to the effects of these on women – in some cases enabling them to move freely (feel secure), in others subjecting them to human rights violations. No mention was found in the literature of persons with disabilities.