The unconfined compressive strength (UCS) of the formation can be used with the mechanical specific energy (MSE) to determine many drilling issues without additional rig time or effort. Clear indications of formation strength changes by UCS permit surface parameters to be adjusted for the maximum ROP in the new formation type and prevent dysfunction while drilling this new formation. Early detection of drill string and bit dysfunction by MSE and mitigation by changing parameters in accordance with UCS improves rate of penetration and may prevent damage to bits and BHA components. Hole cleaning and differential sticking may also be detected and remediated by comparing the behavior of UCS and MSC. This presentation provides the concepts required to work with UCS and MSC and demonstrates with examples from actual drilling operations.