On the eve of the 50th anniversary of the adoption of the Fundamental Principles of the Red Cross and Red Crescent Movement (the Movement) and the 32nd International Conference of the Movement at the end of 2015, as well as the World Humanitarian Summit in early 2016, several initiatives are under way to study the contemporary practice and impact of the Fundamental Principles, and to reaffirm their relevance. The Review decided to contribute to this research and debate, both by soliciting contributions from experts and practitioners in this thematic issue, and in the context of the International Committee of the Red Cross's (ICRC) Second Research and Debate Cycle on Principles Guiding Humanitarian Action throughout 2015, which has hosted a number of substantive discussions on the Principles.