The seismicity of the central New Hebrides convergent plate boundary is investigated with three sets of data: (1) large earthquakes (Ms > 6.9) for the past 75 years, (2) moderate-sized earthquakes (mb > 4.5 and Ms < 7.0) during the past 20 years, and (3) small earthquakes (mb = 2.5 to 4.5) located by local networks for several intervals of 1-2 months each since 1975 and continuously since mid-1978. The second set includes a nearly complete collection of focal mechanism solutions for events with Ms > 5 3/4 and new determinations of accurate focal depths based on analyses of Xwaveforms recorded by WWSSN long-period seismographs. On a regional scale the geometry of the Benioff zone is relatively uniform. Within the resolution of the data there are no major disruptions of the descending plate nor changes in direction of plate convergence along the length of the arc. However, the three data sets all indicate marked variations in the seismicity patterns along the strike of the arc. These variations together with major bathymetric and structural complexities of the interacting plates divide the interplate boundary of the central New Hebrides into segments of about 100 km in length. The segments delimit episodes of seismic rupture but may also differ significantly in the long term balance of seismic versus aseismic slippage. In the segments near Santo and northern Malekula islands seismic rupture of the interplate boundary occurred in complex sequences of large earthquakes during the period 1965-1974, whereas in the segments near southern Malekula and Efate islands seismic rupture of the boundary may not have occurred during the past 75 years. The interaction of a subducted ridge with a preexisting seaward protrusion of the upper plate may result in an increased coupling of the converging plates in the Santo-Malekula segments. The orientation of horizontal compressive stress within the upper plate inferred from focal mechanism solutions and geological data is perpendicular to the arc in the recently ruptured segments but changes in the region between southern Malekula and Efate islands to a more complex and variable pattern found in the southern New Hebrides arc. In addition, the diffuse spatial distribution of small earthquakes in the southern Malekula and Efate segments contrasts with the concentration of small events along the presumed interplate boundary of the recently ruptured Santo segment. The unusual concentration of events at shallow depths within the upper plate in the southern Malekula segment may be evidence for loading of a locked segment of the plate boundary. Unusual features of seismicity suggest that in the Efate segment a significant component of creep may accommodate interplate slippage. A persistently high rate of occurrence of small and moderate-size events (Ms < 6.5) in the Efate segment contrasts with the large fluctuations in activity associated with the major events in the recently ruptured segments. The persistent nest of activity in the Efate segment also contrasts with the relative quiescence in the adjacent segments. The most recent (1978-1979) sequence of three moderatesized shocks (Ms=6) located in the Efate segment was caught by the local networks of seismographs and tilt measurements. Well-documented features of the temporal and spatial development of foreshocks and aftershocks include a clear migration of foreshock activity towards the epicenter of one of the mainshocks. In two cases the area of the aftershock zone expands during a period of several days to a size significantly larger than that expected for the surface wave magnitudes and body wave seismic moments of the mainshocks. For these cases tiltmeter stations on Efate Island, located at distances of 40 to 60 km from the mainshock hypocenters, did not record tilt indicative of post-seismic creep. Nevertheless, periodic releveling of a 1 km benchmark array on Efate reveals that a significant tilt of 3-4 microradians has accumulated during the four year interval between 1976 and 1980. This tilt signal could be indicative of deformation near a transition between a creeping Efate segment and an adjacent locked segment.