Multilateralism has instrumental, institutional and strategic levels, and its development has undergone five periods. These are, pre-Westphalia, Westphalia until the end of World War I, the founding of the League of Nations until the end of World War II, The founding of the United Nations until the end of the Cold War, and the period from the end of the Cold War until the present. Multilateralism has become more frequent, conscious, and wide-reaching over time, and has moved from being a tool to become a strategic choice and forming temporary compromise to becoming a system realizing long term peace. Institutions have become more advanced, and have moved from loose international mechanisms to complete organizations. This historical trend shows that multilateralism has always developed in concert with international relations. It is a part of the progress of human society and is consistent with the tide of world history.