The purpose of this study is to understand how street-level bureaucrats, working with clients with mental illness, are implementing their statutory obligation of support for family carers who are caring for or supporting relatives with mental illness. The study are based on vignettes and qualitative interviews with social workers in three different municipalities in southern Sweden.   The questions of this study are: • How do the social workers communicate their statutory obligation of support to family carers? • How do the social workers distinguish the family carers? • How do the social workers distinguish the family carers who are in need of support?   Metod: Vignettes and qualitative interviews has been used as methods to gather empirical data. Theory: Theories of street-level bureaucracy has been used as theory in the analyses of the empirical material. Results: The result of this study concludes that the social workers, in lack of policy introduction, communicate their obligation to support family carers within their discretion. The result shows that the majority of the municipalities do not have formalized support for family carers supporting relatives with mental illness. The study also concludes that the social workers have different understandings of which family carer who is a carer in need of support. How the social workers, within their discretion, distinguish a carer in need affects which family carers who are offered support. The study also concludes that the social workers have different understandings of which family carers are in need of support.