A comprehensive treatment of federal and state family and medical leave law for employers, employees, and counsel. It builds the FMLA from the ground up: coverage tests including joint employment and integrated employer analysis, the three eligibility requirements and how remote work complicates the 75-mile rule, the four methods of measuring the 12-month period, and each qualifying reason including the post-Obergefell definition of spouse and the in loco parentis doctrine. It develops the serious health condition definition as a test of treatment patterns rather than diagnosis, the two-way notice obligations and their five-business-day clocks, and the full certification apparatus including authentication, clarification, second and third opinions, recertification, and the GINA safe harbor. It then covers leave mechanics, benefits continuation, restoration and the key-employee exception, and the enforcement structure: interference versus retaliation, the prejudice requirement after Ragsdale, sovereign immunity after Hibbs and Coleman, individual supervisor liability, damages, and waiver. The final third addresses the state paid family and medical leave programs now covering a large share of the workforce, how they coordinate with the FMLA, and how to build a leave administration program that works across jurisdictions.