A Central Service Office (CSO) is an AA service office that involves partnership among Groups in a community, just as AA Groups themselves are partnerships of individuals. It is established to carry out certain functions common to all the Groups, functions which are best handled by a centralised office, and it is usually maintained, supervised and supported by these Groups in their own general interest. It exists to aid the Groups in their common primary purpose of carrying the AA message to the alcoholic who still suffers. GUIDELINE NO GL-12