Abstract: When duplicative civil suits proceed simultaneously in both state and federal court, a waste of resources is bound to occur. Nevertheless, the Supreme Court has maintained that federal courts must typically retain jurisdiction over such concurrent litigation. Under the Colorado River abstention doctrine, only “exceptional circumstances,” beyond the mere pendency of a parallel state case, will permit a federal court to relinquish jurisdiction in favor of the state action. How have the lower federal courts responded to this mandate to take jurisdiction, given the inherent waste and confusion engendered by concurrent litigation? And is there a more coherent and efficient way to manage this symptom of our dual federal-state court system? This Note seeks to answer these questions by focusing on the practical application of Colorado River “on the ground” in the lower courts, a subject largely unexplored by the otherwise voluminous scholarship on federal abstention. By surveying decades of cases involving Colorado River abstention in two federal courts of appeals and two district courts, this Note reaches a startling conclusion. Driven by a lack of guidance from the U.S.Supreme Court and a desire to rid their dockets of duplicative suits, the lower courts have taken wildly divergent approaches to Colorado River. The Second Circuit Court of Appeals, for example, has applied the doctrine rigidly, demanding that district courts retain jurisdiction in all but the most exceptional circumstances. Under pressure from this circuit precedent, judges in the Southern District of New York have frequently sought to “effectively” abstain via alternative means, simultaneously relinquishing federal jurisdiction and frustrating appellate review. When they instead attempt to proceed to judgement rather than effectively abstain, the result is typically (and unsurprisingly) a significant waste of judicial resources. On the other hand, the Seventh Circuit has taken a highly permissive view of Colorado River abstention, watering down the otherwise restrictive doctrine. Judges in the Northern District of Illinois have taken up this view with alacrity, abstaining pursuant to Colorado River in the vast majority of cases involving parallel state litigation, subject only to limited and deferential appellate review. This inconsistent doctrinal development could hardly be described as desirable — a combination of informal abstention and judicial waste in the Second Circuit compared with virtually unfettered discretion to formally abstain in the Seventh Circuit. Thus, this Note concludes with a comprehensive proposal to bring greater structure and coherency to the doctrine while avoiding both of these negative results.