The Wales Health Impact Assessment Support Unit (WHIASU) is based in the World Health Organization (WHO) Collaborating Centre on ‘Investment for Health and Well-being’, Policy and International Health Directorate, Public Health Wales. It provides an all Wales Service and provides guidance, training, resources and information in relation to the practice of HIA, which is a method of identifying the health and well-being impacts and addressing health inequalities of policies, plans and proposals, and ‘Health in All Policies’ (HiAP).