The role of evidence during class certification proceedings has evolved significantly since the adoption of the modern class action in 1966. Most notably, in 2011 the U.S. Supreme Court made clear in Wal-Mart Stores, Inc. v. Dukes that certification requires evidentiary proof that Rule 23 of the Federal Rules of Civil Procedure (FRCP) is satisfied. Yet neither FRCP 23 nor the Supreme Court has specified whether the evidence offered must be admissible under the Federal Rules of Evidence (FRE). Without guidance, lower courts are split on the issue. This Comment addresses the split by analyzing whether the FRE should apply to class certification proceedings. To do so, this Comment identifies and applies a framework from cases that held the FRE inapplicable to other proceedings. Because of the class certification proceeding’s preliminary stage, narrow purpose, and discretionary nature, this Comment argues that the FRE need not apply. Rather, judges should have the discretion to consider inadmissible evidence when determining whether to certify a class.