The "Truth in Gender Act of 2025" establishes a federal definition of sex as an individual's immutable biological classification as either male or female, determined at conception by the type of reproductive cell produced. This definition explicitly states that sex is not a synonym for, and does not include, the concept of gender identity. The bill defines "women" and "girls" as adult or juvenile human females, and "men" and "boys" as adult or juvenile human males, based on this biological understanding. The legislation mandates that federal agencies adopt these biological definitions when interpreting statutes, regulations, and guidance, and in all official agency business, documents, and communications. Agencies are required to remove all statements, policies, and forms that promote "gender ideology" and cease issuing such messages. Furthermore, agency forms must require an individual's sex to be listed as male or female, and may not request gender identity. Key provisions include requiring the Secretaries of State and Homeland Security, and the Director of the Office of Personnel Management, to ensure government-issued identification documents and personnel records accurately reflect an individual's biological sex. The bill also prohibits the use of federal funds to promote "gender ideology" and directs agencies to assess grant conditions to ensure compliance. It specifically addresses privacy in intimate spaces , requiring the Attorney General and Secretary of Homeland Security to ensure males are not detained in women's prisons and rescinding certain HUD rules regarding gender identity in shelters. The Attorney General is tasked with issuing guidance to correct the misapplication of Bostock v. Clayton County regarding sex-based distinctions and to protect the freedom to express the binary nature of sex. Federal agencies must submit updates on their implementation of the Act within 120 days, including changes to documents and requirements for federally funded entities. The Act's requirements supersede conflicting provisions in other laws, and agencies must rescind inconsistent guidance documents.