Preferences and Utility.- Barter Exchange.- Welfare Properties of Market Exchange.- Welfare Properties of "Jungle" Exchange.- Economies with Production.- Uncertainty in Exchange.- Externalities.- Public Goods.- Compensation Criteria.- Fairness and the Rawls Criterion.- Life and Death Choices.- Majority Voting.- Arrow's Impossibility Theorem.- Dominant-Strategy Implementation.- Nash Implementation.- Bayesian Implementation.- Epilogue.