A good basic understanding of general equilibrium theory is a fundamental and indispensable background for advanced work in virtually any sub-field of economics; and a thorough understanding of the methods of welfare economics, particularly in a general equilibrium context, is indispensable for investigators undertaking applied policy analysis. This book addresses these needs and requirements by emphasizing the basic underpinnings of general equilibrium and welfare economics. In particular, the theory of choice, which is fundamental to both areas, is developed in a very comprehensive and rigorous fashion. Moreover, extensive use is made of examples, both of the simple type intended to bolster the student understanding of the basic concepts, and those illustrating the application of the material to field areas in economics.