Abstract: The ghost ant, Tapinoma melanocephalum (Fabricius, 1793), is a ubiquitous indoor and outdoor pest throughout much of the tropics and subtropics, and an increasingly common indoor pest in temperate regions. Here, I examine the taxonomy of T. melanocephalum and map records from > 1500 sites to evaluate its worldwide spread and probable geographic origin. I document the earliest known T. melanocephalum records for 154 geographic areas (countries, major islands, island groups, Us states, and Canadian provinces), including many areas for which I found no previously published records: Anguilla, Antigua & Barbuda, Barbados, Bonaire, Cambodia, Cape Verde, Cayman Islands, Comoro Islands, Curaçao, Gabon, Gambia, Grenada, Italy, Kenya, Montserrat, Nevis, Nigeria, Pakistan, Romania, St. Kitts, St. Lucia, St. Martin, Illinois, Michigan, Minnesota, Missouri, North Carolina, Virginia, and Wisconsin. Tapinoma melanocephalum has one of the widest distributions known for any ant species. It has spread across the Old World and New World in both the northern and southern hemispheres, though at latitudes greater than 30° it is largely restricted to living inside buildings. In most parts of the world, T. melanocephalum can be reliably distinguished from other ant species. In India, Southeast Asia, and the western Pacific region, however, T. melanocephalum may be confused with closely related taxa, including Tapinoma minutum Mayr, 1862, Tapinoma indicum Forel, 1895, and several seemingly intermediate forms, suggesting that T. melanocephalum originated in the Indo-Pacific region. Future research on the phylogeny of Tapinoma and on the genetic diversity of T. melanocephalum populations in different parts of the world should help elucidate further the native and exotic ranges of T. melanocephalum.