Reserve Forces' and Cadets' Associations (RFCAs) are Crown bodies in the United Kingdom which give advice and assistance to the Defence Council, and to the Army, Royal Navy and RAF, on matters that concern reserves and cadets. They are contracted by the Ministry of Defence to provide services including management of the volunteer estate, employer support, cadets and youth and to establish and maintain links with the civilian community. Established in 1908 (known then as the County Associations), they are today organised as 13 regional associations, comprising voluntary members and a small full-time secretariat.

Their governing body is the RFCA Council which coordinates their budgets and policies, and is composed of the thirteen voluntary regional chairs. It has a professional chief executive for the council and there is one for each of the 13 regional RFCAs. All key posts have to be approved by the Defence Council but, as a ‘grass roots’ organisation, the names of the voluntary chairs and other officers are submitted after election by the membership, rather than through civil service nomination via the Office of the Commissioner for Public Appointments. The chairman of the council has access to the Secretary of State.

County Associations were established on 1 April 1908 by the Territorial and Reserve Forces Act 1907 to administer the volunteer forces in each county, when the Volunteers and Yeomanry were brought together to form the Territorial Force(TF). The roles of the associations included recruiting, provision and maintenance of buildings and ranges for reserves, arrangements with employers and establishment and support of cadet units. Lord Haldane set them up as he recognised that the War Office and Regular Army had limited links with the civilian world; they helped to fulfil his wider vision of a ‘Nation in Arms’, by ‘building a military structure which shall have its foundations in the nation itself.’ The Associations were: "To render advice and assistance to the military authorities -"the fund of local knowledge possessed by an Association is to be held for the information of the Army Council and of the officers of the Military Commands at need."

The organisation of the Territorial Force in 1907/08 kept the "provinces of command and administration … rigidly distinct…" explained by the fact "that, whereas command and training to be efficient must be centralized, the administration of citizen forces raised on a voluntary basis can only be efficient if it is decentralized. Unity of command and, to some extent, unity of training are essential to success in the field, but diversity and elasticity in administration are no less essential to the encouragement of local effort and the development of local resources in time of peace."

The act was piloted through Parliament in the face of opposition from many quarters including some Conservatives and retired generals arguing for conscription, Labour and pacifist minded-Liberals who were against ‘militarising’ the nation and militia and volunteers opposed to perceived threats to their independence.

The Act provided that each would have the lord-lieutenant of the county as the president and required that at least half of the membership would consist of officers drawn from all branches of the Territorial Force] (or, preceding that, the Yeomanry and Volunteers). Haldane’s plan for local councillors to be compulsorily included were dropped after a political battle, but "Where desirable", members were also to include representatives of the county councils, county borough councils, and universities within the area of the Association, as well as co-opted members representative "of the interests of employers and workmen". From the outset, members elected their officers who appointed each (paid) association secretary who acted as chief executive, although they had to be approved by the Army Council

In June that year, the county associations set up the Council of County Territorial Associations., composing key elected figures from each county association to provide a public voice on behalf of the Territorial Force.

At the outset of the First World War, Kitchener denounced the TF as a ‘town clerks army’ and set up a process for recruiting a parallel organisation of service units (soon called ‘Kitchener units’) for the Regular Army, The county associations and their parliamentary supporters pressed the government to mobilise the Territorial Force and Kitchener agreed that those opting for overseas service should be deployed, with the first units leaving within weeks. Six divisions were deployed to France by April 1915, while the Kitchener formations were still training. General Sir John French, General officer commanding the BEF said ‘Without the assistance which the Territorials afforded between October 1914 and June 1915, it would have been impossible to hold the line in France and Belgium. Besides administering and expanding the Territorial Force, a number of county associations, including Cambridgeshire and East Riding, raised formations for Kitchener's New Armies.