Slip in single crystals of tungsten monocarbide has been observed around Vickers pyramid hardness indentations. The slip plane is {l100} at room temperature and the slip directions are postulated to be the and . The Vickers hardness value on a (0001) face is approximately twice the value determined for a (1100) face. This is attributed to the ease of motion of dislocations with Burgers vectors as opposed to the dislocations having Burgers vectors since the former can dissociate into partial dislocations. The occurrence of a {1100} slip plane is explained on the basis of the fact that a minimum number of only two covalent tungsten-carbon bonds need be broken for a unit of slip on this plane.