This publication is a complete taxonomic revision of the Neotropical ruteline genus Platycoelia. The group occurs mainly in the Andes Mountains of central and northern South America but also extends south to northern Argentina and north through Central America to about México City. The volume is 202 pages and contains 78 figures. There are descriptions, maps, and keys to all taxa as well as a phylogenetic analysis of the group. Taxonomic history, biogeography, natural history, and many other topics are discussed with regards to Platycoelia and the tribe Anoplognathini.