Paleomagnetic, geochemical, and tectonostratigraphic data establish that plate tectonics has been active since at least 3.1 Ga. Reliable paleomagnetic data demonstrate differential horizontal movements of continents in Paleoproterozoic and Archean times. Furthermore, the dispersal and assembly of supercontinents in the Proterozoic requires lateral motion of lithosphere at divergent and convergent plate boundaries. Well-preserved ophiolites associated with island-arc assemblages and modern-style accretion tectonics occur in the Paleoproterozoic Trans-Hudson orogen of the Canadian Shield, the Svecofennian orogen of the Baltic Shield and in the Mazatzal-Yavapai orogens of southwestern Laurentia. These rocks have trace element signatures almost identical to those found in rocks of modern intra-oceanic arcs and include ore deposits typical of modern subduction settings. The discovery of Archean eclogites in the eastern Baltic Shield; the presence of late Archean subduction-related Kuroko-type volcanogenic massive sulfide deposits in the Abitibi greenstone belt of the Canadian Shield; the discovery of mid-Archean island arc volcanics, including the oldest known boninites and adakites; and isotopic data from the world's oldest zircons all argue for modern-style subduction processes possibly back to the Hadean. Seismic images of preserved Paleoproterozoic and Archean suture zones further support this view. These data require a tectonic regime of lithospheric plates similar to the Phanerozoic Earth.