The third edition of this casebook reflects the many developments that have occurred in aggregate litigation since 2013 while continuing to treat the subject as a coherent whole. This edition includes a short, systematic introduction to the range of different aggregation techniques and then pays detailed attention to class actions, multidistrict litigation (MDL), parens-patriae suits, bankruptcy, and arbitration. In particular, this edition features a new chapter devoted to MDL, in which topics range from selecting the transferee court, choosing what law should apply, and exploring the judicial role in examining MDL's effect on settlement and leadership selection. As before, the casebook does more than just present the law--it considers multiple perspectives on policy, litigation strategy, judicial practice, financial considerations, and empirical findings. The book fills three gaps in the market for teaching materials on the U.S. civil justice system. First, it treats "aggregate litigation" as a cohesive field of law that encompasses all devices for processing claims en masse. Second, the book confronts forthrightly the reality of our civil justice system as one geared toward settlement, not trial. From this vantage point, the casebook sees the processes for aggregate litigation as vehicles through which to achieve comprehensive, or broadly encompassing, resolution of related civil claims. Third, the book frames the legitimacy of preclusion in aggregate litigation by drawing, among other things, on conceptions of legitimacy in other settings, such as private contract and public legislation. In so doing, the casebook encourages students to see cross-cutting connections with their other courses on such topics as contracts, corporations, and administrative law.