Treatment of mental disorder according to current diagnostic classification systems has the potential to overlook the importance of addressing individual symptoms in favour of a generalist approach to mental ill-health. This chapter aims to highlight the limitations of the diagnosis of mental disorder and to set out a framework for focusing on individual symptoms of persons experiencing mental ill-health allowing for a more person centred and holistic approach. The approach is not intended to replace pre-existing diagnostic categories but rather aims to complement and enhance current assessment and treatment strategies.