This TechBrief summarizes the results of a study of the GPS-6 experiment, entitled “Performance of Rehabilitated Asphalt Concrete Pavements in the LTPP Experiments—Data Collected Through February 1997.” The GPS-6 experiment, “AC Overlay of AC Pavements,” involves pavement test sections where an asphalt concrete (AC) overlay was placed on an existing AC pavement. The study documents performance trends of the 125 GPS-6 test sections using distress data collected through February 1997. The test sections represent a diverse range of conditions. The age of the overlays range from 0.1 to 26.4 years (with an overall mean age of 7.3 years), while the traffic levels range from 10 to 1,900 thousand equivalent single-axle loads (KESALs) per year (with an overall mean of 300 KESALs per year).