This is an intermediate level textbook in industrial economics. Intended as a text for advanced undergraduate and graduate students specializing in industrial economics, it gives a comprehensive review of theoretical and empirical work, emphasizing the need to relate the two. Part One introduces the subject and traces its history. Part Two discusses various elements of market structure and their relation to the pricing behavior and profitability of firms. Part Three focuses on various aspects of firms strategic behavior. Part Four discusses issues of public policy.