Task 39, FY 1989, "Revision of AASHTO Pavement Overlay Design Procedures" (Darter and Associates). This task was requested by the AASHTO Joint Task Force on Pavements. The objective was to revise Chapter 5 of Part III of the AASHTO Guide for Design of Pavement Structures so that pavement overlay design procedures will yield valid and acceptable designs. Chapter 5 addresses the subject of pavement design procedures for the rehabilitation of existing pavements with overlays. The final report with recommended rewording of Chapter 5 and complete documentation has been completed, verified, and presented to the Joint Task Force. It has been adopted by AASHTO and is included in the latest version of the AASHTO Guide for the Design of Pavement Structures.