This report, commissioned from Knowledge Exchange (KE), is an overview and synthesis of the evolving landscape of Federated Research Data Infrastructures (FRDIs) in the six KE partner countries: Denmark, Finland, France, Germany, the Netherlands and the United Kingdom. The fieldwork and study underlying the report were undertaken by InformAll CIC during the first half of 2017, on the basis of interviews with experts from a range of organisations that run federated infrastructures in the respective countries. The report reaches nine broad conclusions. It first considers the issues and background to the study, then the methodology deployed, before synthesising and analysing the information gathered during the fieldwork. This information is structured to address the following: what is understood by ‘federated’; drivers for FRDIs (push factors and meeting demand); operation of the infrastructures; data-related practices; training and skills; challenges and obstacles; outcomes and impact; and implications for the European Open Science Cloud (EOSC).