Intentional infliction of emotional distress (IIED) is a common law tort claim for intentional conduct that results in extreme emotional distress. The conduct must be beyond the standards of civilized decency and utterly intolerable in a civilized society. Whether the conduct is illegal does not determine whether it meets this standard. IIED is also known as the tort of "outrage," due to a classic formulation of the standard: the conduct must be such that it would cause a reasonable person to exclaim "Outrageous!" in response.

An example of an act which might form the basis for a claim of intentional infliction of emotional distress would be sending a letter to an individual falsely informing the person that a close family member had been killed in an accident.

In civil procedure systems (such as in the United States) that allow plaintiffs to plead multiple alternative theories that may even overlap or contradict each other, a plaintiff will usually bring an action for both intentional infliction of emotional distress and negligent infliction of emotional distress (NIED). This is just in case the plaintiff later discovers that it is impossible to prove at trial the necessary mens rea of intent; even then, the jury may still be able to rule for them on the NIED claim.

There are some reported cases in which a plaintiff will bring only a NIED claim even though a reasonable neutral observer could conclude that the defendant's behavior was probably intentional. This is usually because the defendant may have some kind of insurance coverage (like homeowners' insurance or automobile liability insurance). As a matter of public policy, insurers are barred from covering intentional torts like IIED, but may be liable for NIED committed by their policyholders. See deep pocket .

The U.S. Supreme Court case Hustler v. Falwell involved an IIED claim brought by the evangelist Jerry Falwell against the magazine for a parody ad that described Falwell as having lost his virginity to his mother in an outhouse. The Court ruled that the First Amendment protected such parodies of public figures from civil liability.