The Llano Uplift of central Texas, USA contains large exposures of polydeformed Grenvillian metaigneous and metasedimentary rocks that were intruded by late- to post-orogenic granites. New U-Pb and ⁴⁰Ar/³⁹Ar single mineral ages and Rb-Sr mineral isochrons document the retrograde cooling history that followed Grenville-age metamorphism in the north-central and northeastern Llano Uplift, and explain discrepancies between previous U-Pb crystallization ages and younger determinations based on Rb-Sr and K-Ar isotopic systems. Dating has been carried out in the Valley Spring Gneiss (VSG) and the post-tectonic Lone Grove Pluton (LGP) in three areas of the Llano Uplift, from west to east: VSG rocks in the Babyhead area north of Llano, Texas, yielding hornblende, muscovite and biotite ⁴⁰Ar/³⁹Ar ages and Rb/Sr mineral isochron ages from ~1098 to ~1014 Ma; a sample from the LGP at Petrick Quarry, yielding U-Pb titanite and hornblende and biotite ⁴⁰Ar/³⁹Ar ages from ~1096 to ~1076 Ma; and VSG samples from the Inks Lake area in the eastern Llano Uplift, yielding U-Pb titanite, hornblende and biotite ⁴⁰Ar/³⁹Ar, and Rb-Sr mineral isochron ages from ~1087 to ~1029 Ma. Titanite from the Oatman granite to the southwest of these areas yields a U-Pb age of 1119±6 Ma. These ages, combined with closure-temperature estimates, document cooling in the Llano Uplift from ~1100-1000 Ma at rates between 5 and 14°C Ma^-1. Although rapid uplift following early high-pressure metamorphism has important regional thermal effects, the cooling rates documented in this study are interpreted to represent the relaxation of local geotherms following local magmatic activity. The low-temperature history documented in this study is probably unrelated to uplift rates. This supports the suggestion that magmatic heating was an important factor in the late high-temperature/low-pressure metamorphism of the Llano region. It further suggests that the late pressure and temperature conditions recorded in the rocks were likely not synchronous across the region.