Historical Introduction. Market Equilibrium: A First Approach. Production Decisions and the Boundedness of the Economy. Consumer Decisions and Efficient Allocations. The Existence of Competitive Equilibrium. General Equilibrium under Alternative Assumptions. Markets with Non-Convex Preferences. The Core of a Market Economy. The Uniqueness of Competitive Equilibrium. Comparing Equilibria. Introduction to Stability Analysis. Stability with Recontracting. Trading out of Equilibrium: A Pure Exchange Economy. The Keynesian Model. Mathematical Appendix A: Positive Matrices. Mathematical Appendix B: Convex and Related Sets. Mathematical Appendix C: Fixed Point Theorems and Related Combinatorial Algorithms. Indexes.