An updated infrageneric classification is provided for the genus Agave L. s.l., therefore including A. subg. Manfreda, i.e., the genera Manfreda Salisb., Polianthes L., and Prochnyanthes S.Watson (Asparagaceae: Agavoideae / Agavaceae), with emphasis on the rank of section. Nomenclatural assessments are provided for (1) all unranked infrageneric ‘group’ names introduced by Trelease (1913) for the Caribbean region, by (2) Gentry (1982) for continental North America, and (3) for all infrageneric taxa at sectional rank hitherto published in Agave by Salm-Dyck, Engelmann, Berger, Ullrich, Webb & Starr, Starr & Webb, and Hochstätter. We also show that Jacobi did not publish names at the rank of section. In addition, a revised infrageneric classification of Agave s.l. is provided, including new combinations and new names mainly at the rank of section, especially for those unranked group names used by Trelease (1913) and Gentry (1982) for which no corresponding formal name at sectional rank is available. Three new combinations are made in Agave for species recently described in Manfreda and Polianthes.