In United States law, diversity jurisdiction is a concept used in civil procedure to refer to the situation in which a U.S. (federal) district court has subject matter jurisdiction to hear a civil case because the parties are "diverse" in citizenship, which generally indicates that they are citizens of different states (corporate parties, and non-U.S. citizens can also be included). Diversity jurisdiction and federal question jurisdiction (i.e., jurisdiction over issues arising under federal law) constitute the two primary sources of subject matter jurisdiction in U.S. federal courts.

The United States Constitution, in Article III, § 2, gives the U.S. Congress the power to permit federal courts to hear diversity cases through legislation authorizing such jurisdiction. The provision was included because the framers of the Constitution were concerned that when a case is filed in one state, and it involves parties from that state and another state, the state court might be biased toward the party from that state. Congress first exercised that power and granted federal trial circuit courts diversity jurisdiction in the Judiciary Act of 1789. Diversity jurisdiction is presently codified at 28 U.S.C. § 1332.