This chapter examines the phenomenon of the multijurisdictional, or cross-border, class action. Several high-profile consumer class actions, dealing with grievances from breast implants to lost competition prizes, have comprised cross-border class actions. Lawmakers from around the Comparator Jurisdictions have taken entirely disparate views as to how to deal with non-resident class members. Some have insisted that such class members proactively opt in to the domestic class action, whilst others have taken a more liberal view, or have omitted to deal with the matter legislatively at all. Whichever legislative tack has been adopted, the concept of cross-border class actions raises important issues of private international law.