This is a list of pals battalions (also called "service" or "locally raised" battalions) of the British Army during the First World War. Pre-war Territorial Force (T.F.) battalions have not been included, although they too usually recruited from a specific area or occupation. The 69 line infantry regiments formed 142 locally raised battalions and 68 local reserve battalions.^[1] The Guards Regiments^[2] and the regiments formed only from Territorial Force battalions^{[3][lower-alpha 1]} did not form pals battalions.

Lord Kitchener was one of the few people in 1914 to realise that the First World War was not going to be a short one; he believed that it would last three years and would require an army of 70 divisions. He eschewed the Territorial Force – partly due to the limitations imposed by its terms of service but also due to the poor impression he formed when observing the French Territorials in the Franco-Prussian War – and did not make use of the framework envisioned by Haldane's Reforms. He launched his appeal for 100,000 volunteers on 7 August 1914 to form a first New Army of six divisions (and support units) and within a few days this target had been reached; by the end of September, half a million volunteers had come forward to form the New Armies.^[1]

Each of the 69 line infantry regiments raised one battalion for the First (K1)^{[lower-alpha 2]} and for the Second New Armies (K2)^{[lower-alpha 3]} designated as "service" battalions and numbered after the existing Territorial Force battalions of their parent regiments. This rigid structure did not take account of the differing ability of regiments to raise troops based upon the population of their recruiting areas. Therefore, the Third New Army (K3) had a much higher proportion of battalions from the more populous north of England, notably Cheshire, Lancashire, Yorkshire, Durham and Northumberland. The Fourth New Army (K4) was formed from men of the Reserve and Special Reserve battalions which were over establishment. Originally formed into the 30th – 35th Divisions, these were broken up so the battalions could train recruits and send drafts to the first three New Armies.^[1]

While the first four New Armies were being raised, a number of "service" battalions were also being raised by committees in cities and towns, and by other organizations and individuals. These units were recruited on a more narrow basis than usual, such as men who worked in a specific occupation or at a certain business, and were popularly known as "pals battalions". These were housed, clothed and fed by their committees until the War Office took them over in 1915 and the raisers' expenses were refunded. These units formed the Fifth and Sixth New Armies (later called the new Fourth and Fifth New Armies when the original Fourth New Army was broken up).^[1]

The locally recruited battalions also formed depot companies and in 1915 these were grouped into "reserve" battalions to provide reinforcements for their parents. They became part of the Training Reserve on 1 September 1916.^[12]