This Practice Note discusses key considerations for employers seeking to enforce a release of claims in a settlement or separation agreement with an employee. This Note addresses the legal framework for defending against a lawsuit that violates a release, waiver, or covenant not to sue, including the knowing and voluntary requirement for the release of Title VII and other federal employment discrimination claims, special requirements under the Older Worker Benefits Protection Act (OWBPA) for releasing Age Discrimination in Employment Act (ADEA) claims, validity of the release under ordinary contract law principles, applicability of the tender back doctrine, and more. This Note addresses federal law and litigation in federal court but provides examples of state law considerations.