This final rule implements a legislative provision on milk substitutes that is consistent with current regulations on menu exceptions for students with disabilities and adds requirements for the optional substitution of nondairy beverage for fluid milk for children with medical or special dietary needs in the National School Lunch Program and the School Breakfast Program. Specifically, this final rule establishes nutrient standards for nondairy beverage alternatives to fluid milk, allows schools to accept a written substitution request from a parent or legal guardian, grants schools discretion to select the acceptable nondairy beverages, and continues to make school food authorities responsible for substitution expenses that exceed the federal reimbursement. This rule ensures consistency of standards among milk substitutes offered in the school lunch and breakfast programs, and assures that students who consume nondairy beverage alternates receive important nutrients found in fluid milk.