The Llano Uplift of central Texas records middle Proterozoic tectonism and metamorphism that has not been overprinted by subsequent events, unlike other Grenville-aged provinces in Canada and the Appalachians. This project will concentrate on U-Pb geochronometry integrated with field, petrographic, and analytical data constraining the timing of sequential deformational, meta- morphic and intrusive events will test several current hypotheses of the tectonic setting of the Precambrian margin of North America. Results of this study of the Llano Uplift are expected to be applicable to understanding the evolution of the Grenville orogen along the entire margin.