The Northern Ireland Civil Service Alliance (NICSA) was a trade union representing civil servants working in Northern Ireland. The union was founded in 1922 as the Association of Established Civil Servants, representing workers in the recently-established Civil Service of Northern Ireland. Membership grew steadily, reaching 800 by 1925, but then stalled. In 1934, the union took advice from William Brown of the British Civil Service Clerical Association, and on his recommendation, it renamed itself as the Association of Civil Servants in the Government of Northern Ireland and began accepting temporary staff.