People with mental health problems are frequent victims of anti-social behaviour but they may also be perceived as anti-social. There is a danger that people may move towards criminalisation if no solution can be found. This research project explored tensions between anti-social behaviour policy and challenges for statutory and third sector organisations to support vulnerable people who experience mental health problems. We collected qualitative data in the form of 60 narrative police logs and interviews with service users and carers (n = 56) and professionals (n = 55). Service users and carers were involved in all stages of the project, ranging from the research development to dissemination. An inductive thematic approach was used to identify patterns within and across the data. Findings suggest that there are no clear-cut categories of victim and perpetrator and people may move in and out of these categories over time. In addition, although there is a legal definition of anti-social behaviour, professionals from different backgrounds and service user and carer interpret behaviours differently, partly depending on contextual and social-cultural factors. This has a major impact on relationships and ultimately on access to and experience of services by service users and carers.