Editors' Summary: In Harmon Industries, Inc. v. Browner, the Eighth Circuit held that once a state with an authorized RCRA program has taken an enforcement action against a defendant, EPA may not maintain a separate enforcement action based on the same set of facts, a practice commonly referred to as "overfiling." The Eighth Circuit held that the Agency's practice of overfiling violated both the language of RCRA and the doctrine of res judicata. This decision has enormous significance for EPA's RCRA enforcement policy, because for years, EPA has asserted the right to overfile whenever it decides that the relief sought in a parallel state action is inadequate. This Dialogue summarizes the essential facts and proceedings that led to the Eighth Circuit's decision and then analyzes the court's holdings. It ends with a discussion on the implications of the Harmon case, concluding that the decision is sound both as a matter of legal analysis and federal-state enforcement policy.