The following sections are described and illustrated in this book: Agaricus sez. Bivelares, Agaricus sez. Chitonioides, Agaricus sez. Xanthodermatei, Agaricus sez. Hondenses, Agaricus sez. Sanguinolenti, Agaricus sez. Bohusia, Agaricus sez. Nigrobrunnescentes, Agaricus sez. Lanosi, Agaricus sez. Agaricus, Agaricus sez. Rarolentes, Agaricus sez. Spissicaules, Agaricus sez. Subrutilescentes, Agaricus sez. Arvenses, Agaricus sez. Minores. The majority of the species are sequenced and represented with illustrations that comes from original description of the species. English language. The volume is composed by 520 pages and 677 photos.