This volume contains ten essays on seminal topics in economic theory by internationally renowned scholars.

1. The economics of social networks; 2. Multi-contracting mechanism design; 3. Allocative and informational externalities in auctions and related mechanisms; 4. The economics of relationships; 5. Information in mechanism design; 6. Communication in economic mechanisms; 7. Advances in dynamic optimal taxation; 8. Quantitative macroeconomic models with heterogeneous agents; 9. Modeling inefficient institutions; 10. Whither political economy? Theories, facts, and issues; 11. Comments on Acemoglu and Merlo.