Personal budgets aim to increase choice and independence for people with social care needs but they remain underused by people with mental health problems compared to other disability groups. The use of personal budgets may impact on families in a variety of ways, both positive and negative. This paper draws on interviews, undertaken in 2012-2013 with 18 family carers and 12 mental health service users, that explored experiences of family involvement in accessing and managing personal budgets for a person with mental health-related social care needs. The sample was drawn from three sites across England, with additional carers being recruited via voluntary sector networks. Our findings show that for many people with severe mental health needs who lack motivation and confidence to negotiate access to personal budgets, carers may provide the necessary support to enable them to benefit from this form of social care support. We illustrate the role carers may play in initiating, pursuing and maximising the level of support available through personal budgets. However, some carers interviewed considered that personal budget funding was reduced because of practitioners' assumptions about carers' willingness and ability to provide support. We also report perceived tensions between family carers and practitioners around appropriate involvement in decision-making. The study findings have implications for local authorities, practitioners and family carers in supporting the involvement of family carers in support for people with severe mental health problems.