The Post-Implementation Review of the Health and Act 2022 is a three-year (2023-2026) research project commissioned by NIHR Policy Research Programme (PRP ST-01-49 ). Co-led by Dr Marie Sanderson and Dr Jonathan Hammond, the project is a collaboration between researchers from London School of Hygiene and Tropical Medicine, The University of Manchester, and University of Kent. It aims to build an evidence base concerning the development and governance of collaboration in Integrated Care Systems; identify appropriate metrics for assessing the impact and outcomes of this collaboration, and; disseminate findings to support local ICS practice, and support policymakers with future policy.