Dr Agnew has been involved in delivering mental health services in the Cook Islands and Samoa. He has provided leadership in the development of Pacific mental health and addiction services in the wider Auckland region and has served on many government agencies and reviews. He is an Executive Board member of the Pasifika Medical Association. He is a fellow of the Royal Australian and New Zealand College of Psychiatrists and a Fellow of the Australasian Chapter of Addiction Medicine. Dr Agnew has served as the Zonal Representative (Australia, New Zealand and the Pacific Islands) for the World Psychiatric Association (WPA). He is the Metua for the Pacific Mental Health Commission.