The abstention doctrine articulated by the Supreme Court in 1941 in Railroad Commission of Texas v. Pullman Co. calls for federal courts to postpone asserting jurisdiction over federal constitutional challenges to state laws to permit state courts to resolve potentially dispositive ambiguities in those laws. In preemption cases, however, many courts have declined to abstain under Pullman, despite the fact that preemption challenges to state laws raise the very federalism-based concerns that the Pullman doctrine was designed to address. When a state law is challenged on grounds that it is preempted by a federal law, ambiguous and potentially dispositive matters of state law often remain undecided. A federal court’s refusal to abstain in such cases risks the possibility of needless interference with state programs, unseemly conflict with state courts, or superfluous or premature adjudication of federal issues. This Note argues that federal courts should invoke Pullman abstention in preemption cases using a flexible, case-by-case analysis that preserves the ability of federal courts to vindicate federal rights without jeopardizing core principles of judicial federalism or wasting scarce resources.