Common and radiogenic Pb isotopic compositions of plagioclase and anti-perthitic feldspars from granulite-facies lower crustal xenoliths from the Labait Volcano on the eastern margin of the Tanzanian Craton have been measured via laser ablation MC-ICP-MS. Common Pb in plagioclase and a single stage Pb evolution model indicate that the lower crust of the Tanzanian Craton was extracted from mantle having a 238 U/ 204 Pb of 8.1 ± 0.3 and a 232 Th/ 238 U of 4.3 ± 0.1 at 2.71 ± 0.09 Ga (all uncertainties are 2σ). Since 2.4 Ga, some orthoclase domains within anti-perthites have evolved with a maximum 238 U/ 204 Pb of 6 and 232 Th/ 238 U of 4.3. The spread in Pb isotopic composition in the anti-perthitic feldspars yields single crystal Pb–Pb isochrons of ∼ 2.4 Ga, within uncertainty of U–Pb zircon ages from the same sample suite. The Pb isotopic heterogeneities imply that these granulites resided at temperatures b 600 °C in the lower crust of the Tanzanian Craton from ca. 2.4 Ga to the present. In concert with the chemistry of surface samples, mantle xenoliths, and lower crustal xenoliths, our data imply that the cratonic lithosphere in Tanzania formed ca. ∼ 2.7 Ga, in a convergent margin setting, and has remained undisturbed since 2.7 Ga.