- Rule 14(a)(1): a defendant can join a non-party (third-party defendant) who is or may be liable to defendant for ALL or PART of the claim against the original plaintiff - An impleader claim allows defendant to assert claims for indemnity or contribution against a third-party defendant for the claim the defendant is defending. - Court must have PJ over impleaded party, generally the court will have supplemental jurisdiction (indemnity and contribution are state claims so no fed question juris) - Once a third-party defendant is joined, they may make claims of her own against other parties as long as SMJ exists over EACH CLAIM (usually exists through supplemental) - The original plaintiff may assert claims agains the third-party defendant arising from the same transaction or occurrence as plaintiff's original claim against the original defendant