Abstract UPb zircon systematics for granitic and gneissic clasts from the Moodies conglomerate of the Barberton Greenstone Belt, South Africa, exhibit discordancy patterns that suggest variable and multi-episodic lead loss and indicate crystallisation ages for the parent granitoids between 3.3 and 3.47 Ga. Metamict zircons in some of these clasts indicate complete resetting of the older material or new growth at about 2.8–2.9 Ga ago that is ascribed to a regional thermal event as also shown by published RbSr data for a nearby granitoid pluton. Since the Moodies clasts consist largely of potassic granites our ages suggest the presence of highly evolved continental crust in the source region of the greenstone belt sediments, a feature that contradicts the commonly accepted model for the primitive nature of the granitoid crust in early Archaean granite-greenstone terrains. The maximum age of 3.3 Ga for the Moodies Group also shows that greenstone belt evolution in the Barberton region took place over a period of at least 150 Ma from about 3450 to 3300 Ma ago. The Kaap Valley and Stentor plutons intrude the lower part of the greenstone succession, and their diapiric emplacement caused large-scale deformation of earlier structures in the entire greenstone belt sequence at about 3.23–3.25 Ga ago. Detrital zircons in the sediments of the Fig Tree Group date the mean age of their source terrain at c. 3520 Ma which is also the maximum age of deposition for these strata. This age is indistinguishable from the oldest age reported from the Barberton greenstones and suggests the possibility that pre-greenstone granitoid crust may exist in the eastern Kaapvaal craton.