The Agaricales are an order of fungi in the class Agaricomycetes (division Basidiomycota). It is the largest group of mushroom-forming fungi, and includes more than 600 genera and over 25,000 species. [1] Molecular phylogenetics analyses of ribosomal DNA sequences have led to advances in our understanding of the Agaricales, and substantially revised earlier assessments of families and genera. [2] The following families are in the Agaricales, according to Kalichman, Kirk & Matheny (2020), [3] with more recent additions and amendments, as noted. The number of genera and species in each family is taken from Catalogue of Life (2023), [1] unless otherwise noted, and is subject to change as new research is published. Many genera are not as yet assigned to a family.