A motion to dismiss is a formal request (usually in a written motion) asking the court to dismiss a lawsuit or case for one of the reasons described in the relevant state or federal rule of civil procedure.

A motion to dismiss is usually filed in the early stages of the litigation and may be required before the party files any other pleading. Some of the common bases on which a case may be dismissed by the court include: (1) statute of limitations expired; (2) lack of subject-matter jurisdiction; (3) lack of personal jurisdiction; (4) improper venue; (5) insufficient process; (6) insufficient service of process; (7) failure to state a claim upon which relief can be granted; and (8) failure to join a party.

In Massachusetts, a motion to dismiss is governed by the Massachusetts Rules of Civil Procedure, specifically Rule 12(b). This rule allows a defendant to request the court to dismiss a case on several grounds, including lack of subject-matter jurisdiction, lack of personal jurisdiction, improper venue, insufficiency of process, insufficiency of service of process, failure to state a claim upon which relief can be granted, and failure to join a necessary party. The motion to dismiss is typically filed early in the litigation process, often before the defendant files an answer to the complaint. If the statute of limitations has expired on the plaintiff's claim, this can also be a ground for dismissal. The court will consider the motion and, if it finds merit in the arguments presented, may dismiss the case either with prejudice (meaning the case is closed and cannot be refiled) or without prejudice (allowing the plaintiff to correct the issues and possibly refile).