This book contains the texts of the main lectures presented at the NATO Advanced Studies Institute on "Advances in Preparation and Properties of Stereoregular Polymers" held at Tirrenia near Pisa, Italy, from October 3 to 14, 1978. A few contributed papers have also been included because they were concerned with topics not included in the main lectures. The primary objective of the Institute was to assist in the further development of stereoregular polymers because of the ever-increasing demand for new products with exceptional chemical and physical properties. This need has reawakened interest in the field. Indeed there is now a rapidly increasing activity in the study of stereoregular polymerization and the preparation of structurally-ordered polymers with the aim of achieving apprecia ble improvements in existing polymeric materials through new developments in synthesis and properties as well as in discovering new polymeric structures. In order to achieve these objectives, a broad interdiscipli nary cooperation among scientists involved in investigations on the design, synthesis, characterization and application of stereo regular or structurally-ordered polymers will be necessary.