This bill, known as the "Securing Actual Female Events in Olympic Sports Act," amends title 36, United States Code, to establish new eligibility requirements for amateur athletes in Olympic and other sanctioned athletic competitions. It mandates that national governing bodies (NGBs) adopt a rule requiring amateur athletes to participate only in events corresponding to their biological sex . This requirement applies to a wide range of events, including the Olympic Games, Paralympic Games, Pan-American Games, and various national, regional, and local competitions. The bill explicitly defines "sex" as a person's immutable biological classification as male or female, determined at conception by the biological function of producing sperm or eggs. Furthermore, the legislation addresses the sanctioning of amateur athletic competitions by NGBs. It requires NGBs to continue sanctioning single-sex competitions (male-only or female-only) that meet existing requirements and were sanctioned within the past decade. The bill also prohibits NGBs from rescinding sanctioning or altering sex-based competition categories for events previously sanctioned, unless necessary to comply with the new biological sex participation rule. However, it clarifies that NGBs are still permitted to sanction competitions that include both males and females.