Although the US is the largest single contributor of funds to the UN, it is also the largest debtor, owing over $1.2 billion to the world body. The growth of US arrears is primarily the result of UN peacekeeping operations which more than tripled in number during the 1990's. US reluctance to pay off the debt is breeding resentment among UN members and undermining US influence. This thesis strives to develop an in-depth understanding of the processes and policies used by the US government to provide financial resources to the United Nations. A focused review of pertinent literature and public law sheds light on how the numerous limitations on US spending for the UN threaten the fiscal well- being of the United Nations. The UN budget structure, the congressional budget process, and major factors influencing US spending for the UN are explored, as well as the implications of continued US reluctance to pay its UN debts. Major findings are that the growth of US arrears is a result of increased fiscal constraints within the US budget, the politics linking US funding for the UN to international family planning (abortion), and pressure for the UN to initiate administrative and peacekeeping policy reforms.