This volume presents a sequence of articles which describe the theoretical treat- ments of investigating the fundamental features in the electronic structures and properties of typical quasi-one-dimensional solids; organic conductor TTF-TCNQ, polyacetylene, metallic and superconducting polymer (SN)n and linear chain chal- cogenides and halides of transition elements including NbSe3' The aim of this volume is not to present an exhaustive review but rather to touch on a selective class of problems which appear to be fundamental for typical quasi-one-dimensional solids. Thus the topics in this...