The police have underdeveloped links with mental health and social care services despite daily contact with mentally ill individuals. They struggle with identifying and managing the mentally ill in custody, and consistently express a lack of support from partner agencies. In 2010, our research team developed a mental health screening tool and pathway for use by police custody officers, The Police Mental Health Screening Questionnaire (PolQuest). However, due to the large number of agencies with different organisational goals and responsibilities that deal with mentally disordered offenders, the introduction of a screening tool alone was considered insufficient. Thus, an action learning group comprising key professionals from relevant services in one geographical area was tasked with developing a manual and training materials to support the implementation of PolQuest by frontline staff. This paper reflects upon the key themes that emerged from the experience of action learning as a method for engaging multi-agency staff, operating under different occupational goals and cultures, to develop shared practice-oriented outcomes. Data analysed include the facilitator’s reflective notes, meeting minutes and emails. The action learning process was considered a useful method for engaging multi-agency stakeholders in developing materials to support PolQuest’s implementation in vivo.