Abstract: Thirty-nine of the papers presented at the 1981 International Conference on Underground Plastic Pipe are included. The types of pipes examined include: thermoplastics, thermosetting plastic (with special attention to polyethelene, PE, and polyvinyl chloride, PVC) and reinforced thermosetting resin and reinforced plastic mortar pipes. The key topics are structural design, flexibility installation, strain, deformation, deflection, monitoring and aging. Many papers address water and sewage transport, and the issues of soil/pipe interaction are also covered. Sample paper titles include, Butt Fusion of Large Diameter Polyolefin Pipe and Cyclic Pressure Tests of Class 150 C-900 PVC Pipe. The conference was sponsored by the ASCE Pipeline Division with the assistance of the Plastics Pipe Institute, the Reinforced Plastics/Composite Institute and the Uni-Bell Plastics Pipe Association. Illustrations and detailed charts accompany most papers.