The analysis of strategic choice by noncooperative agents has come a long way since Augustin Cournot first developed a model of such behavior in his 1838 work, Researches into the Mathematical Principles of the Theory of Wealth. The current volume is a celebration of the publication of Cournot's model of multiagent behavior and an examination of its relevance and importance to economic theory and analysis 150 years after its first appearance. The contents of this volume will encompass both old and new. It includes contributions by Cournot, Bertrand, and Nash as well as recent papers that focus on the properties and uses of Cournot's model of competition among the few. These papers reflect a revival of interest in Cournot's model due largely to increased emphasis by economists on capturing elements of imperfect competition and strategic behavior (for a sample of other recent articles, see the Extended Bibliography at the end of this chapter). This expansion of interest is not limited to microeconomics; recent work in macroeconomics has also started to feature imperfect competition as an integral part of the analysis. The reason for this renaissance is clear: Cournot developed the basic model of noncooperative behavior by agents and it is to variations on this model that economists turn when imperfect competition is analyzed.