Collective redress has gained momentum in Europe and North America. Legal reforms are driven by different institutional conditions but show a limited degree of convergence. In this book, seventeen contributions from the US, Canada, and the Member States of the European Union put the interplay of public enforcement and private collective judicial enforcement into perspective. The parameters of analysis are the constitutional dimension (i.e. three multi-level systems compared US, EC, and Canada, vertically: allocation of powers between levels and distinction between regulation and private law and administrative control versus judicial control; horizontally: degree of harmonization, trans-border litigation, choice of law), the institutional dimension (the players, regulatory and judges, private organization and lawyers) and the substantive dimension (regulation through administrative law versus regulation through tort or contract law, standard setting (strict liability versus negligence), remedies (injunctions and damages). These three parameters are then broken down into five sections: general comparison, the public/private enforcement divide, remedies concerning the distinction between injunction and damages as well as between class actions and group actions, negotiation and adjudication, trans-border litigation and international private law. The final chapter develops prospects to indicate the way ahead.