Recent seismic tomography imaging shows clear evidence for southwestward subduction along the entire length of the New Guinea Trench (NGT) in Indonesia and Papua New Guinea. Viewed in conjunction with the occurrence of large (Mw > 7) thrust earthquakes that are known to have occurred on the trench, this confirms conclusions of earlier studies that the NGT is an active, inter-plate boundary. The ~650 km long slab is visible to a depth of about 300 km and subducts with a dip angle that varies from ~30¿ at 136¿E to ~10¿ at 143¿E. The improved clarity of the seismic tomography in this region stems from the use of a more accurate data set of P- and S-wave arrival times and hypocentral locations.