After the end of the Cold War and the collapse of communism in Poland, the main goal for the Polish nation was integration into the Western collective security organizations. Poland's democratically elected politicians initiated a process that aimed at NATO membership for Poland. The first steps included adjustment of Polish civil-military relations, diplomatic efforts to push for early inclusion, and the adoption of a democratic constitution. Polish determination, in conjunction with the U.S. steps influencing NATO decision-making to enlarge the Alliance finally resulted in NATO inclusion of Poland in 1999. This thesis seeks to determine which forces, events and personalities contributed to Poland's NATO membership. Moreover this thesis will be a useful example for such future potential NATO members such as Ukraine and Croatia in their applications for NATO membership. The steps that Poland took to comply with NATO requirements, as well as the manner in which Polish diplomats pushed for enlargement, could be used as an example to follow. Additionally, descriptions of the United States' and other NATO members' policies and contributions to NATO enlargement will allow for understanding of the importance of the organization.