A method is developed for predicting cutter forces, temperatures, and wear on PDC bits as well as integrated bit performance parameters such as weight-on-bit, drilling torque, and bit imbalance. A computer code called PDCWEAR has been developed to make this method available as a tool for general bit design and analysis. The method uses single-cutter data to provide a measure of rock drillability and employs theoretical considerations to account for interaction among closely spaced cutters on the bit. Experimental data are presented to establish the effects of cutter size and wearflat area on the forces that develop during rock cutting. Waterjet assistance is shown to significantly reduce cutting forces, thereby potentially extending bit life and reducing weight-on-bit and torque requirements in hard rock. The effects of several other design and operating parameters on bit life and drilling performance are also investigated.