This study explored a new partnership between Victoria Police and mental health services to improve response to individuals experiencing mental health crisis. It charted organisational change and examined system dynamics in the Police, Ambulance and Clinical Early Response model. Findings indicated the level of symbiotic interdependency achieved and a perceived improvement to police response to people with mental illness. They also highlighted the importance of measures to establish trust, boundaries and expectations between services as well as to address organisational and cultural differences.