A position within a legislative body, charged with the security of the body, maintaining order, and other ceremonial and support duties.

In the United Kingdom, Sergeants-at-Arms began in 1279, under Edward I. His were a group of 20 bodyguards. In 1415, the British Parliament adopted the post. In this (and other British Commonwealth) Parliaments, an ornamental mace and sword are carried. The contemporary Sergeants-at-Arms continue to be charged with maintaining order and decorum on the floor, and perform ceremonial duties.

In the US Senate, the Sergeant-at-Arms was created in 1798, evolving out of the position of doorkeeper. It is his (or her) role to perform such duties as escort officials such as the President at official functions, arranging for funerals of senators who die in office, and orienting new members. The Sergeant-at-Arms is the chief law enforcement official in the Capitol and related office buildings, and authorized to detain individuals. Telecommunications, printing and graphics, and other administrative functions are also run by the office of the Sergeant-at-Arms.

This role is duplicated in other parliamentary bodies (state houses, Canadian provincial bodies, clubs and organizations), for similar security and logistical purposes.