Service Dress is the style of khaki service dress uniform introduced by the British Army for use in the field from the early 1900s, following the experiences of a number of imperial wars and conflicts, including the Second Boer War. This variant of uniform continues to be worn today, although only in a formal role, as No. 2 Pattern dress.

During the latter half of the nineteenth century, the bright red tunics worn by British infantry regiments had proved to be a liability, especially when during the First Boer War they had been faced by enemies armed with rifles firing the new smokeless cartridges. This had been exacerbated by the white cross-belts and ammunition pouches worn by the line infantry

The term Khaki (Persian for dusty) had come from India and was used to describe the 'Drab' uniform first worn in 1848 by the Corps of Guides. During the Indian Mutiny of 1857 many British regiments took to staining their white tropical uniforms with tea leaves or other makeshift dyes in order to camouflage them. Rifle regiments had long used dark green uniforms (with blackened badges, buttons, and carrying equipment) as camouflage and some units of the Volunteer Force London Regiment had adopted Hodden grey uniforms for the same purpose. Numerous khaki drill uniforms were adopted by units in the field over the turn of the century but the darker khaki standardised Service Dress uniform was not adopted until after the Second Boer War. First publicly displayed in 1902, the new uniform did not become universal issue until the following year for all of the regular army serving in Britain.

Scarlet, dark blue and rifle green uniforms were retained as "review order" (parade) and "walking out" (off duty wear out of barracks) until 1914. After World War I they were reintroduced only for the Brigade of Guards, Household Cavalry, regimental bands and for other limited purposes such as wear by officers attending levees.

For Other Ranks, the SD uniform originally comprised khaki wool (serge) trousers, a khaki wool tunic, with stand-and-fall (or Prussian) collar, four pockets on the front, each buttoned closed by a flap with a straight (horizontal) edge, large, serge reinforcement patches over each shoulder, shoulder straps and a pair of brass wire hangers on the back, over the kidneys, to support the belt. The front of the jacket was closed by five buttons, usually of a regimental pattern, brass for most regiments and corps, but black for rifle regiments, arranged vertically. A peaked cap was provided, covered in the same khaki serge (including the stiff peak), with a leather chin strap (brown, for most regiments) held at either side by brass or horn buttons. This uniform was worn with ankle Ammunition boots; in the field, Puttees would be wound up (or down) the length of the shins, covering the top of the boots. The carrying equipment worn by infantry with this uniform was normally the 1908 Pattern Webbing, made of fabric and also khaki (though a lighter shade than the uniform).

Cavalry and gunners of the Royal Regiment of Artillery did not wear webbing equipment, but instead used the leather 1903 Bandolier Equipment, worn over one shoulder. Originally derived from the bandoliers carried by the Boer commandos during the Second Boer War, it had been found to be unsuitable for infantry use but remained in service with mounted troops. Headgear was initially a forage cap without a peak, similar to those worn by the German Army; it was known as the "Brodrick cap", named after St John Brodrick, the Secretary of State for War. This proved to be unpopular and was replaced in 1905 by the now familiar peaked cap; however, the Brodrick cap was retained by the Royal Marines until 1930. In late 1914, the Winter Service Dress Cap was introduced; it had a soft peak and crown with woollen ear flaps that could be buttoned together over the top. It was commonly known as the "Gorblimey" cap, allegedly from the expletive uttered by sergeant majors when they first saw them. They were not much used after mid-1916.

The Officers' Service Dress was completely different, except in colour. The cloth used was tailored and of more expensive wool, and the tunic had longer skirts. After 1908 the turn-down collar was replaced by open stepped lapels. This created a jacket, similar to a civilian lounge suit, rather than a tunic, and revealed a shirt collar and tie; the shirt was initially white and the tie black; but from 1913 these were both replaced with khaki. The breast pockets were pleated and closed by scalloped flaps, while those at the hips had straight edges. There was a shoulder strap on each shoulder but rank was originally displayed on the cuffs, which were scalloped at the closure and edged with herring-bone pattern khaki tape. Trousers, or riding breeches, and brown leather Riding boots were worn (even in infantry regiments, as officers traditionally rode on campaign). The carrying equipment was the leather Sam Browne pattern, brown for most regiments, black for Rifle Regiments. Officers also wore a khaki peaked cap with a cloth visor that was similar to the men's, but made of superior materials and of better quality. Unlike other ranks, officers were expected to pay for their own uniforms, pistol, sword and Sam Browne belt.

Scottish Highland pattern uniforms differed in the wearing of tartan kilts or trews, rather than trousers or breeches and in alterations in the design of the tunic and jacket to make them resemble the traditional Highland doublet type – notably in cutting away the skirts at the front of the tunic to allow the wearing of a sporran. Most Scottish regiments did not wear the service dress peaked cap but either the Glengarry or Tam O'Shanter.