According 34 CFR 460.4 [Title 34 – Education; Subtitle B -- Regulations of the Offices of the Department of Education; Chapter IV -- Office of Vocational and Adult Education, Department of Education; Part 460 -- Adult Education -- General Provisions], the term adult basic education means “instruction designed for an adult who--
(1) Has minimal competence in reading, writing, and computation;
(2) Is not sufficiently competent to meet the educational requirements of adult life in the United States; or
(3) Is not sufficiently competent to speak, read, or write the English language to allow employment commensurate with the adult's real ability.
If grade level measures are used, adult basic education includes grades 0 through 8.9.”