This upper-level undergraduate text provides an introduction to industrial organization theory along with applications and nontechnical analyses of the legal system and antitrust laws. Using the modern approach but without emphasizing the mathematical generality inherent in many of the arguments, it bridges the gap between existing nontheoretical texts written for undergraduates and highly technical texts written for graduate students. The book can also be used in masters' programs, and advanced graduate students will find it a convenient guide to modern industrial organization. The treatment is rigorous and comprehensive. A wide range of models of all widely used market structures, strategic marketing devices, compatibility and standards, advertising, R&D, as well as more traditional topics are considered in versions much simplified from the originals but that retain the basic intuition.