This paper describes the application of system dynamics to assist decision making in the reallocation of resources within a specialist mental health trust in south London. Mental health service providers are under increasing pressure to both reduce their own costs and to move resources upstream in mental health patient pathways to facilitate treating more people, whilst not compromising service quality. The investigation focuses on the use of the model to examine the case for converting an existing specialist service ward in a mental health hospital into a ‘triage’ ward, where patients are assessed and prioritised during a short stay for either discharge or onward admission to a normal ward. Various policies for the transition are studied together with the implications for those patients needing post hospital services and relocation within the community. The model suggests that the introduction of a triage ward could meet the strategic requirement of a 10% shift away from institutional care and into community services. The paper includes a number of statements from the management team involved on the benefits of system dynamics to their thinking.