Professor Ezawa has written an extremely useful book on the theory of the Quantum Hall Effect. The book covers a wide range, starting from the spectacular discoveries of the Hall conductivity plateaus all the way to the most recent developments in double-layer systems. Even experiments on the Josephson-like effects in double layers, performed only in this millenium, are analysed. The book will be particularly appreciated by physicists interested in double layer systems using a field theoretic approach. The first portion of the book offers a detailed introduction to the ideas and techniques in field theory relevant to the field. These are then used to analyse different aspects of quantum Hall physics in terms of systematic, unified derivations. That is a particularly valuable feature for students since the original literature in the field employs a diverse mix of intiution and explicit derivations, using variously first and second quantised formulations. The book is also very attractively produced with numerous graphs and colorful figures to illustrate the ideas.