Broadband receiver functions developed from teleseismic P waveforms recorded on the midperiod passband of the Department of Energy's Regional Seismic Test Network station RSNY are analyzed to examine the crustal structure beneath the Adirondack Highlands of upstate New York. Radial receiver functions are inverted in the time domain to determine the vertical shear velocity structure at four distinct back azimuths. Lateral changes in structure are identified by examining azimuthal variations in the vertical structure. Southeast or RSNY, our model consists of a thick crust, including a broad crust-mantle transition. The most prominent structure is a high-velocity zone (shear velocity >4.0 km/s) between 18 and 26 km depth which overlies a lower crust of low average shear velocity (<3.7 km/s). The extent of the high-velocity zone correlates in depth with a highly reflective zone in Consortium for Continental Reflection Profiling profiles SE of RSNY, while the deep low-velocity zone may be correlated with a broad electrical conductivity anomaly in the Adirondacks. This general structure is also seen SW of RSNY, but is more difficult to document at NW and NE azimuths. ¿American Geophysical Union 1987