  We present the results of a new HI, optical, and H-alpha interferometric
study of the nearby spiral galaxy NGC 157. Our combined C- and D-array
observations with the VLA show a large-scale, ring-like structure in the
neutral hydrogen underlying the optical disk, together with an extended, low
surface density component going out to nearly twice the Holmberg radius.
Beginning just inside the edge of the star-forming disk, the line of nodes in
the gas disk commences a 60 degree warp, while at the same time, the rotation
velocity drops by almost half its peak value of 200 km/s, before leveling off
again in the outer parts. While a flat rotation curve in NGC 157 cannot be
ruled out, supportive evidence for an abrupt decline comes from the ionised gas
kinematics, the optical surface photometry, and the global HI profile. A
standard `maximum-disk' mass model predicts comparable amounts of dark and
luminous matter within NGC 157. Alternatively, a model employing a disk
truncated at 2 disk scale lengths could equally well account for the unusual
form of the rotation curve in NGC 157.
