The concrete overlay on asphalt (COA) is a rehabilitation alternative consisting of a 100 to 175 mm (4 to 7 in.) thick portland cement concrete overlay of an existing flexible or composite pavement. When designed and built properly, the COA can provide 20 years of good serviceability on most of non-interstate roadways. This report is part of ongoing research conducted by the University of California Pavement Research Center for the California Department of Transportation. The report evaluates existing mechanistic-empirical procedures for designing this type of pavement.