This thesis deals with the conceptual-theoretical classification of Assertive Community Treatment (ACT), an evidence-based treatment model for people with severe mental illness founded in the US. This model works in the setting of a multidisciplinary team which is reachable 24 hours a day and works at the clients homes. The model is implemented in several european states, where it is considered differentiated. Based on a comparison with the concept of clinical social work, the ACT is examined in a literature-based analyses. Overlapping theoretical constructs and demarcations of ACT and clinical social work are discussed and brought together in the question of mutual enrichment. Possible enrichments lie in the broad theoretical background of clinical social work and the evidence-based care model of the ACT. Interviews with experts were conducted in the Viennese social psychiatry care system to validate the results of the concept analyses. An ACT approach in conjunction with the socio-therapeutic focus of clinical social work can, in respect of its outreach setting, close a gap in the care system through its intensive care approach addressing psychosocial factors, implementation of the UN Convention on the Rights of Persons with Disabilities and by offering care for the group of hard-to-reach clients.