This book explores the terra incognita of nationality requirements in Olympic sports, providing not only a comprehensive overview of the different sports, but also placing them in the wider context of the international standards of nationality law. The following questions are examined: what are the eligibility criteria currently employed by the Olympic sports? To what extend is it problematic to align these currently applicable eligibility criteria with international standards of nationality law? How can tensions that may exist between the criteria applied by the sporting federations and the international standards of nationality law be solved?