Full text can be accessed at http://jgs.lyellcollection.org/content/152/6/911.shortNd isotopic data from samples collected across the Tanzanian sector of the Mozambique belt indicate that the bulk of the belt consists of early Proterozoic crust which was tectonothermally reworked during Pan-African time. The only evidence for younger crust is preserved in granulite complexes that are surrounded by older amphibolite-facies gneisses. The uniformity of crustal formation ages of the gneisses across most of the belt indicates that models explaining the Mozambique belt as a tectonic collage of terranes with different pre-Pan-African crustal histories are invalid.