This report by Professor Jay Tidmarsh of Notre Dame Law School examines five cases in which Rule 23 of the Federal Rules of Civil Procedure has been used to achieve a settlement of a mass tort controversy. The reason for studying mass tort settlement class actions is simple: Using class actions for this purpose has been, and is, controversial. The mass tort settlement class action was the subject of a significant decision in the last term of the Supreme Court, and it is also the subject of a proposed amendment to Rule 23 that has been under consideration by the Advisory Committee on the Federal Rules of Civil Procedure. There has been considerable debate both about the idea of settlement class actions in general and about the proposed amendment in particular. There have also been a number of case studies or anecdotal descriptions about mass torts in which settlement classes have been used. Thus far, however, the studies and descriptions have been narrowly focused on only one case or on only some of the issues relevant to the propriety of settlement class actions.