The basic institutional structure and functions of the WHO were a reflection of efforts by its creators to forge a new organization, as a core part of the post-war order, from new aspirations for more concerted international health cooperation, and pre-existing health bodies and their political constituencies. Of particular importance was the need to unite the latter, as part of this new endeavor, through clear leadership and unrivalled technical expertise. The result was a threetiered organization which, in principle, enabled the WHO to combine centralized policy leadership with decentralized operational capacity. In practice, the appropriate distribution of staff, financial resources and, perhaps most importantly, decision-making power across the headquarters, regional and country levels has remained an ongoing source of tension.