Linear chain substances span a large cross section of contemporary chemis try ranging from covalent polymers, organic charge transfer complexes to nonstoichiometric transition metal coordination complexes. Their common ality, which coalesced intense interest in the theoretical and experimental solid-state-physics/chemistry communities, was based on the observation that these inorganic and organic polymeric substrates exhibit striking metal-like electrical and optical properties. Exploitation and extension of these systems has led to the systematic study of both the chemistry and physics of highly and poorly conducting linear chain substances. To gain a salient understanding of these complex materials rich in anomalous anisotropic electrical, optical, magnetic, and mechanical properties, the convergence of diverse skills and talents was required. The constructive blending of traditionally segregated disciplines such as synthetic and physical organic, inorganic, and polymer chemistry, crystallography, and theoretical and experimental solid state physics has led to the timely devel opment of a truly interdisciplinary science. This is evidenced in the contri butions of this monograph series. Within the theme of Extended Linear Chain Compounds, experts in important, but varied, facets of the discipline have reflected upon the progress that has been made and have cogently summarized their field of specialty. Consequently, up-to-date reviews of numerous and varied aspects of "extended linear chain compounds" has developed. Within these volumes, numerous incisive contributions covering all aspects of the diverse linear chain substances have been summarized. I am confident that assimilation of the state-of-the-art and clairvoy ance will be rewarded with extraordinary developments in the near future.