The purpose of this technical memorandum is to provide a summary of work that has contributed to the development of the simple shear test as a tool to evaluate the performance of asphalt concrete (AC) mixes. It is based primarily on investigations at the Pavement Research Center, University of California, Berkeley, related to the definition of the stiffness and permanent deformation characteristics of AC mixes. While the discussion is concentrated on the SHRP-developed simple shear test, some information is presented on the uniaxial and triaxial modes of loading as well. This discussion includes the following: 1. the mechanics of permanent deformation in AC; 2. factors to be considered in test selection including: representative volume element; non-linear response; test specimen preparation; and static versus dynamic loading. 3. use of the simple shear tests for mix evaluation including mix design This memorandum has been prepared to provide information related to activities at the national level directed to the development of a performance test to be included as part of the Superpave mix design and analysis procedure.