Analysis of foraminiferal assemblages from the Viséan–Serpukhovian boundary interval in Britain has led to the recognition that levels correlated with the first occurrence of Lochriea ziegleri at the base of the Serpukhovian Stage can be established by the foraminifer Neoarchaediscus gregorii in England and Scotland, which first occurs from the Single Post and Cockleshell limestones in northern England and laterally equivalent levels, as well as Asteroarchaediscus bashkiricus, and A. rugosus (except for South Wales). Contrary to some previous studies, the base of the Serpukhovian does not equate with the base of the Namurian (Pendleian Substage), but lies approximately at the early–late Brigantian boundary, based on the first occurrence of Neoarchaediscus postrugosus. Four foraminiferal assemblages are distinguished in the early Serpukhovian (7–10) and four assemblages in the late Serpukhovian (11–14). Despite the contrast in facies, it is now recognized for the first time that throughout the Midland Valley of Scotland, northern England and South Wales the foraminiferal assemblages from shallow-water platform facies are completely compatible with the ammonoid subzones from deep-water basinal facies, with no apparent mismatches. There appears to be close comparability of foraminiferal assemblages and first appearance data of marker species with most of the international foraminiferal zonal schemes in Russia.