This stage comprises multiple case study design to explore in-depth community engagement and trust in healthcare for Gypsy/Travellers . The unit of analysis is the approach to engagement between health services and Gypsy/Traveller communities within a locality. Each case study involves interviews, focus group discussions and documentary analysis. Four case studies will be selected purposively to reflect the diversity of Gypsy/Travellers communities, different approaches to community engagement, and examples of good practice regarding maternity, early years’ or child dental health services (identified through the realist synthesis and online consultation). Three case studies will be in England and one in Scotland to reflect the larger population of Gypsy/Travellers in England and to meet the funders’ remit of advising policymakers in England. The selection of a case study in Scotland strengthens the methodology because there are differences between healthcare structures and remuneration in England and Scotland that could be significant.