A discriminatory school district is sued, placed under court supervision, remedies the discrimination, and is released from court supervision. What next? There is a growing, and worrisome, trend towards the resegregation of schools following their release from supervision. While the problems of resegregation have recently drawn attention among social scientists and journalists, the procedural hurdles to litigating a claim of resegregation remain largely unexamined. Indeed, certain procedural hurdles could greatly impede litigation to challenge resegregation. This Note examines the defense of preclusion in the resegregation context, and concludes that in two categories of cases—pre-1966 class actions, and post-1966 “implied” class actions—school districts cannot rely on preclusion to defeat an action challenging resegregation. The first category, pre-1966 class actions, were filed before the 1966 Amendments to Rule 23, which provide greater procedural protections to ensure adequate representation. The second category, implied class actions, were filed after the 1966 amendments, never formally certified as class actions, but informally treated as such by courts. Because many pre-1966 class actions and post-1966 implied class actions do not provide the procedural protections to satisfy the constitutional requirement for adequate representation, judgments releasing school districts from court supervision cannot properly bind future plaintiffs challenging resegregation.