A combination drilling and wrenching tool which has three basic components, an inner housing for holding a drill bit, an intermediate housing for holding the inner housing, and an outer housing for holding the intermediate housing. The intermediate housing has an inner shank for insertion into the chuck of a power tool and a forward shank which has a bore for receiving the inner housing. The outer housing has a forwardly facing drive socket for wrenching and a rearwardly facing socket for receiving the forward shank of the intermediate housing in a rotary driving relationship. The outer housing has a bore which extends forwardly from the rearward socket for receiving the front end of a drill bit which is mounted in the inner housing. More specifically, a plurality of inner housings are utilized. Each inner housing has the same external cross-sectional dimension, but the inner housings have different horizontal bore sizes for accommodating drill bits of different sizes.