This book is a timely review of recent advances on the construction and functions of organic thin films by a variety of techniques. The component molecules are relatively simple ones with self-organizing properties, i.e., ordered molecular assembly characteristics. The contents are arranged from the fundamental concepts of molecular assembly of self-organizing molecules to the potential biological applications of protein assemblies, supramolecular species.Recently, many promising applications for new electric, magnetic or optical devices, biomimetic membranes etc. have been the subject of investigation. However, fundamental studies on molecular assembly characteristics and functions for mono-, bi- and multi-layers, Langmuir-Blodgett films are indispensable to future technological innovations for molecular electronic devices and biological sensors.