This chapter draws on research undertaken in a large Metropolitan force in England and Wales and presents two case studies which problematise the issue of policing and mental health in two environments. Both scenarios discuss the implications of inadequate problem definition in the police and mental health context, the impact on the type of knowledge applied in decision making, the differing elements of risk that this poses and the need for police practitioners to work with other health professionals in these situations to improve outcomes. The first case study is based on research which sought to define victim typologies in rape cases in London following reviews focused on the long-term and continuing problem with attrition (cases leaving the criminal justice process at the police stage) (Stern, 2010; Angiolini, 2015). This is despite the implementation of a dedicated rape project to prioritise improving this area of policing in 2000. The second case study is based on a piece of work which explored practitioners’ perceptions of dealing with mental health and vulnerability in custody suites, the missed opportunities within that environment to glean data about the client population and the impact this has on decisions to deliver more proactive strategies to improve outcomes. Both case studies strongly reinforce the need to better understand the complexity of both individual and context-specific demand when dealing with vulnerability and mental health in policing. The chapter concludes with an overview of the current situation from the perspective of a police practitioner leading on the national agenda for the College of Policing (CoP). It is clear from the evidence presented here that the risks of ineffective problem definition and the subsequent reactive nature of dealing with this complex issue places victims, suspects and those in crisis at risk and, without doubt, the officers involved in policing this space.