This is a set of three volumes containing edited versions of papers and a commentary presented at invited symposium sessions of the Ninth World Congress of the Econometric Society, held in London in August 2005. The papers summarize and interpret key developments, and they discuss future directions for a wide variety of topics in economics and econometrics. The papers cover both theory and applications. Written by leading specialists in their fields, these volumes provide a unique survey of progress in the discipline.

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. 1. Empirical models of auctions; 2. Identification in models of oligopoly entry; 3. Empirical models of imperfect competition: a discussion; 4. Recent developments in the economics of Price discrimination; 5. Bounded Rationality in Industrial Organization; 6. Price discrimination and irrational consumers: discussion of Armstrong and Ellison; 7. Behavioral economics; 8. Incentives and self-control; 9. Discussion of behavioral economics; 10. Dynamic models for policy evaluation; 11. Microeconometric search-matching models and matched employer-employee data; 12. Discussion of 'dynamic models for policy evaluation' and 'microeconometric search-matching models and matched employer-employee data; 13. Field experiments in development economics; 14. Institutions and development: a view from below 1. Identification of non-additive structural functions Andrew Chesher; 2. Non-additive models with endogenous regressors Guido W. Imbens; 3. Heterogeneity and microeconomics modeling Martin Browning and Jesus Carro; 4. Heterogeneous choice Rosa L. Matzkin; 5. Modeling heterogeneity Arthur Lewbel; 6. Inference with weak instruments Donald W. K. Andrews and James H. Stock; 7. Empirical likelihood methods in econometrics: theory and practice Yuichi Kitamura; 8. Weak instruments and empirical likelihood: a discussion of the papers by D. W. K. Andrews, J. H. Stock and Y. Kitamura Richard J. Smith; 9. Estimating continuous-time models with discretely sampled data Yacine Aït-Sahalia; 10. Variation, jumps and high frequency data in financial econometrics Ole E. Barndorff-Nielsen and Neil Shephard; 11. Discussion of Aït-Sahalia and Barndorff-Nielsen and Shephard Oliver Linton and Ilze Kalnina; 12. Understanding bias in nonlinear panel models: some recent developments Manuel Arellano and Jinyong Hahn; 13. Fixed and random effects in nonlinear panel data model, a discussion of a paper by Manuel Arellano and Jinyong Hahn Tiemen M. Woutersen.