Abstract The Recent world fauna of Sciaroidea, or fungus gnats, comprises approximately 4000 described species in eight families: Bolitophilidae, Cecidomyiidae, Diadocidiidae, Ditomyiidae, Keroplatidae, Lygistorrhinidae, Mycetophilidae, and Sciaridae. Larvae live primarily in decaying vegetation, feeding on fungal mycelia, and they can be among the most abundant insects of temperate forests. Stem-group families appeared in the Jurassic, with large Tertiary deposits being composed almost entirely of living genera, so the Cretaceous is essential for understanding the origins and diversification of Recent families. Sixty-six specimens were studied from six major deposits of Cretaceous amber, spanning 40 million years from the Early to Late Cretaceous: Lebanon (ca. 125 Ma), northern Spain (120 Ma), northern Myanmar (Burma) (ca. 105 Ma), northern Siberia (two sites, 105 and 87 Ma), New Jersey (90 Ma), and western Canada (80 Ma). New taxa are the following: Docidiadia burmitica (n.gen., n.sp.) (Diadocidiidae); ...