Geodetic observations of the January 29, 1994 M 5.1 aftershock of the Northridge earthquake are consistent with seismic solutions showing left-lateral oblique slip on a northeast striking steeply dipping fault. Thirty second solutions of the data from the station showing the maximum observed displacement (35 mm) indicate neither precursory nor immediate post-seismic motion to the aftershock. The aftershock does appear to be superimposed over the longer term Northridge post-seismic deformation field. Inversions of the data yield a potency of 2.6¿0.3¿10-3 km3 slightly higher than that determined by seismic methods. Combining the potency with estimates of rigidity from P- and S-wave velocities yields a moment that is consistent with seismic moment solutions. ¿ 1998 American Geophysical Union