Mess dress is the military term for the formal evening dress worn in the mess or at other formal occasions. It is also known as mess uniform and mess kit.

British and Commonwealth Armies

Mess uniforms first appeared in the British Army in about 1845. The original purpose was to provide a relatively comfortable and inexpensive alternative to the stiff and elaborate full dress uniforms then worn by officers for evening social functions such as regimental dinners or balls. With the general disappearance of full dress uniforms after World War I, mess dress became the most colourful and traditional uniform to be retained by most officers in British and Commonwealth armies.

The form varies according to regiment, corps or service, but generally a short mess jacket is worn, which either fastens at the neck (being cut-away to show the waistcoat; this was traditionally the style worn by cavalry regiments), or is worn with a white shirt and black bow tie (traditionally the usual style for all other regiments, corps and services). Since the regimental amalgamations of recent years, the "cavalry style" jacket has been adopted by most British Army regiments and corps, although the simpler "infantry style" uniform remains popular in Commonwealth armies.

Most British Army regiments' mess dress incorporates high-waisted, very tight trousers known as "overalls", the bottoms of which buckle under heeled boots (or "mess wellies"). Ornamental spurs are usually worn in cavalry regiments; some other regiments and corps prescribe spurs for "field officers" (majors and above), since in former times these officers would have been mounted.

The colours of mess jackets and overalls usually reflect those of the traditional full dress uniforms of the regiments in question, as worn until at least 1914. Thus, jackets are usually scarlet, blue or green, with collars, cuffs, waistcoats or lapels in the former facing colours of the regiments in question. Scottish officers may wear kilts or tartan trews according to occasion or regimental practice.

Royal Navy

Mess dress is generally worn as the military equivalent of white tie or black tie. However, the Royal Navy and some other navies distinguish between mess dress, which is now the equivalent of civilian white tie, and mess undress, which is the equivalent of black tie. Before 1939, there were three forms of evening dress, with the most formal, ball dress, including a tailcoat and gold epaulettes. Mess dress included trousers with gold lace. Today there is no ball dress, and the only difference between mess dress and mess undress in the Royal Navy is the colour of the waistcoat, which is white for mess dress and blue (or replaced with a cummerbund) for mess undress.

Officers of the rank of Captain and above still wear tailcoats for both mess dress and mess undress.

Royal Air Force

Mess dress in the Royal Air Force is similar to that in the Royal Navy, except that the jacket and trousers are in mid-blue. For the most formal occasions, such as court balls and royal evening receptions, a white bow tie is worn with a white waistcoat. However for all other evening events, a black bow tie with a mid-blue waistcoat or a slate grey cummerbund is worn. Cummerbunds of a particular squadron or unit design may also be worn. On Scottish units, a kilt of grey Douglas tartan may be worn.

United States Armed Forces

Mess dress in the United States Armed Forces is a more recent trend, which started in the early 20th Century.

U.S. Army

In 1902, when the U.S. Army introduced its last standing collar dress blue uniform, an evening dress uniform, a modified civilian "tail coat" was introduced, and was worn with a white tie and vest. After World War II, the evening dress and mess dress uniforms were reintroduced, with the "tail coat" having a single "Austrian knot" over the branch-of-service color (General Officers had stars over an oak-leaf braid), with the rank placed in the bottom opening of the knot, while the mess coat, for black-tie affairs, used an Austrian knot rank system, with the branch insignia at the bottom. The number of knots indicated the officers rank: five for Colonel, four for Lt. Colonel, three for Captain, two for First Lieutenant, and none for Second Lieutenant. This complicated system was replaced with the evening coat style (which lost its "tails" in the late 1960's) in 1972, using a single knot and the rank placed above the branch-of-service color. A white mess coat, for summertime wear, was introduced in the 1950's.

U.S. Navy and Coast Guard

Both the U.S. Navy and U.S. Coast Guard utilize the same mess uniform, consisting of a black waist-length "tuxedo" coat with rank stripes on the sleeves, and worn with a white bowtie and vest for state occasions, or a black bowtie and gold cummerbund for semi-formal occasions. A white coat with black shoulder boards is worn for the summer.

A second set of standards exists, for personnel under the rank of Lieutenant (O-3) using the standard dress uniform. These simply replace the ribbons worn on the left with minature size medals. Enlisted who are E-6 (Petty Officer First Class) and below wear their standard dress uniform, the traditional sailor suit, with miniature medals, or a uniform similar to the officers, but with rank insignia and service stripes on the left sleeve.

U.S. Air Force

The U.S. Air Force wear an identical pattern to the USN, except that coat and trousers are dark blue, black bow ties and dark blue cummerbund are used for black tie affaris and white bow tie with white waist coat for white tie affairs, shoulder boards and silver wrist braid replace the rank stripes (enlisted members wear sleeve rank insignia instead of shoulder boards), and silver buttons replace the gold buttons. Enlisted members also have the option to wear the Semi-Formal, essentially an issued service dress with a white shirt substituted for the blue shirt, but most non-commissioned officers elect to purchase a mess dress.

U.S. Marine Corps

The U.S. Marine Corps, since the late 19th Century, has worn the most elaborate of the mess dress uniforms in the US Armed Forces. The uniform coat is fastened at the neck, similar to that of the Dress Blue uniform, but is left open, cavalry style, to expose the shirt and cummerbund, which is scarlet (General Officers have a scarlet vest with small gold buttons). Rank, in gold or silver wire, is embroidered directly on the shoulder epaulets, which is bordered with gold wire and scarlet piping (as is the collar), with the cuffs, also bordered in gold wire and scarlet, having a "quatrefoil"--the coiled rope-like decoration found on the officer's cap, for Warrant Officers and Junior Commissioned Officers (2d Lieutenant to Captain), a single row of oak leaves for Senior Commissioned Officers (Major to Colonel), and a double row of oak leaves for General Officers. The uniform is complete with black trousers with gold & red stripes, and a "boatcloak," a black knee-length cape line in scarlet silk. Staff Non-Commissioned Officers (Staff Sergeant to Sergeant Major/Master Gunnery Sergeant) wear a mess uniform similar to that of the Navy's officers, except with the traditional light blue trousers with "blood stripe," scarlet cummerbund, and black bowtie.