This monograph provides a detailed account of 308 species of the Lycaenid subtribe Polyommatina, with comprehensive descriptions and illustrations of their genitalia. The main text thoroughly describes each taxon, covering the original description, type locality, distribution, taxonomic notes, and detailed structure of the male genitalia, while also discussing the differences between closely related species. It features 38 color plates of adult specimens, which generally show the upperside and underside of both male and female specimens. The volume also includes enlarged, black and white line drawings of the male and female genitalia, which illustrate and explain the structurally important diagnostic features for identification.