Opinion of the Court
We therefore face the question whether, consistent with the FAA, an ambiguous agreement can provide the necessary “contractual basis” for compelling class arbitration. Stolt-Nielsen, 559 U. S., at 684. We hold that it cannot—a conclusion that follows directly from our decision in Stolt-Nielsen. Class arbitration is not only markedly different from the “traditional individualized arbitration” contemplated by the FAA, it also undermines the most important benefits of that familiar form of arbitration. Epic Systems, 584 U. S., at ___ (slip op., at 8); see Stolt-Nielsen, 559 U. S., at 686–687. The statute therefore requires more than ambiguity to ensure that the parties actually agreed to arbitrate on a classwide basis.
A
The FAA requires courts to “enforce arbitration agreements according to their terms.” Epic Systems, 584 U. S., at ___ (slip op., at 5) (quoting American Express Co. v. Italian Colors Restaurant, 570 U. S. 228, 233 (2013)). Although courts may ordinarily accomplish that end by relying on state contract principles, First Options of Chicago, Inc. v. Kaplan, 514 U. S. 938, 944 (1995), state law is preempted to the extent it “stands as an obstacle to the accomplishment and execution of the full purposes and objectives” of the FAA, Concepcion, 563 U. S., at 352 (internal quotation marks omitted). At issue in this case is the interaction between a state contract principle for addressing ambiguity and a “rule[] of fundamental im-
signed,” post, at 14. Justice Sotomayor, on the other hand, concludes that the contract is ambiguous about class arbitration but criticizes us for treating the contract as… ambiguous. Post, at 2–3 (dissenting opinion). Again, we simply follow this Court’s ordinary approach, which “accord[s] great deference” to the courts of appeals in their interpretation of state law. Expressions Hair Design, 581 U. S., at ___, (slip op., at 7) (quoting Pembaur v. Cincinnati, 475 U. S. 469, 484 n. 13 (1986) (collecting cases)).
