  This paper discusses our ongoing efforts to characterize dust-enshrouded
Wolf-Rayet (WR) stars in the radio and infrared. We have used the Very Large
Array to measure the broadband radio spectrum of WR stars in suspected binary
systems and discovered non-thermal emission, which is usually attributed to
colliding winds. In addition, infrared imaging using aperture masking
interferometry on the Keck-I telescope has resolved the dust shells around a
number of WR stars with K-magnitudes brighter than ~6. Although this admittedly
small study suffers from selection bias, we note that all the dust-enshrouded
WR stars with radio detections show evidence for colliding winds, supporting
the theory that wind compression in a binary system is necessary for efficient
dust production. A consequence of this hypothesis is that virtually all WC8-10
stars must be in binaries, since most are dusty. Single-star and binary stellar
evolution models will have to be modified to accommodate this observational
result if confirmed.
