Structural organization or disorganization in macromolecular systems has been an important subject of polymer physical chemistry during the last one or two decades. This volume summarizes the main lectures presented at the Osaka University Macromolecular Symposium OUMS '98 on Molecular Interactions and Time-Space Organization in Macromolecular Systems, where the following topics were discussed:crystallization kinetics, liquid crystals, phase separation, gelation, adhesion, complex formation, and self-organization, with emphasis on molecular interactions. Both these topics are hot issues at present and frequently are taken up as a main theme at a particular symposium. The present symposium invited leading theorists and experimentalists in these fields as guest speakers and is expected to attract the interest of a significant range of readers.