Vary by course type: adult education programs may require placement testing; some career training / skills programs may require a high school diploma or equivalent; prior coursework in a related field may be required for advanced courses; enrichment courses typically have no prerequisites (learn.org)
Holistic Nutrition students may also apply for transfer credit for prior coursework. (pacificrimcollege.com)
A Ph.D. student who has completed at least one full term of satisfactory work may file an application for transfer of prior coursework done at HGSE to be counted toward their degree. (gse.harvard.edu)