Public health institutes have an important role in promoting and protecting the health and well-being of populations. A key focus of such institutes are the wider determinants of health, embracing the need to advocate for ‘Health in All Policies’ (HiAP). A valuable tool to support this is the health impact assessment. This scoping study aims to support public health institutes to advocate more successfully for the use of health impact assessments and HiAP in order to promote and protect health, well-being and equity. It highlights the enablers and barriers to the use of HIA in the contexts of the participants and suggests some actions which PHIs can take and Units they can learn from. The results from this study can serve as a platform to help build knowledge, networks and expertise, to help support a ‘Health in All Policies’ approach and address inequalities which exist in all societies.