The frilling of Colorado Corehole No. 3 was a part of a cooperative program with the Atomic Energy Commission to investigate sites for pilot experiments concerning in situ processing of oil shale. The well was drilled to evaluate a potential site for a subsurface nuclear explosion designed to fracture oil shale in place. This paper presents the procedures for the drilling of the well and results obtained. Two other wells were previously drilled by the USBM in the northwestern part of the Piceance Creek basin to obtain data on the subsurface oil shale deposits.