The first ever Illustrated Checklist of the Birds of the World is really two works in one. It is a complete checklist whose taxonomy incorporates the most up-to-date information and an exhaustive methodology (Tobias et al. 2010) in an entirely systematic and consistent way. At the same time, it contains illustrations and distribution maps for every bird species in the world. This includes the original artwork from the HBW series, as well as hundreds of new illustrations, all in two compact volumes (Volume 1: Non-passerines & Volume 2: Passerines). Volume 2: Passerines: 1 order, 138 families, 1,358 genera, 6,592 extanct species, 57 extinct species. 1,013 pages, 446 plates, 12,629 bird illustrations (including 642 new and 1.208 improved) and 6,649 distribution maps. Taxonomic results: In this Checklist, with the guidance of many genetic studies and the aid of the scoring system employed to evaluate differences in morphology, vocalizations, ecology and geographical relationships, the number of taxonomic changes for the passerines has been significantly high. At present (totals may change slightly before publication), the current volume has 41 lumps and 628 splits, compared with the taxonomy presented in the HBW series.