Robert's Rules of Order, often simply referred to as Robert's Rules, is a manual of parliamentary procedure by U.S. Army officer Henry Martyn Robert. "The object of Rules of Order is to assist an assembly to accomplish the work for which it was designed [...] Where there is no law [...] there is the least of real liberty". The term "Robert's Rules of Order" is also used more generically to refer to any of the more recent editions, by various editors and authors, based on any of Robert's original editions, and the term is used more generically in the United States to refer to parliamentary procedure.

Robert's manual was first published in 1876 as an adaptation of the rules and practice of the United States Congress to the needs of non-legislative societies. Robert's Rules is the most widely used manual of parliamentary procedure in the United States. It governs the meetings of a diverse range of organizations—including church groups, county commissions, homeowners associations, nonprofit associations, professional societies, school boards, and trade unions—that have adopted it as their parliamentary authority. Robert published four editions of the manual before his death in 1923, the last being the thoroughly revised and expanded Fourth Edition published as Robert's Rules of Order Revised in May 1915.