NATO expansion is a key issue both within NATO and in the context of alternative future security alignments in Europe involving NATO, the European Union (EU) and Western European Union (WEU), the Organization for Security and Cooperation in Europe (OSCE), and the Commonwealth of Independent States (CIS). States in Central and Eastern Europe are seeking membership in NATO. NATO has responded with outreach programs, most recently the Partnership for Peach (FPF) Program. NATO leaders have said they expect and welcome NATO expansion as an evolutionary process in which FPF will play an important role. In the public debate, officials and scholars have made many arguments in favor of expansion, against it, and to defer it. There appears to be general support in Congress, the American and European publics, and the executive branches in NATO states for inviting Central and Eastern European states, particularly the four Visegrad states of the Czech Republic, Hungary, Poland, and Slovakia, to join NATO, but no decisions have been made nor dates established. Russian officials have been ambivalent but often object to expansion of NATO to include Central and Eastern European states but not Russia. NATO is conducting a study to address how NATO might expand and what the implications would be. Among the issues that may be raised are: whether additional criteria for membership should be specified, which states should be invited, when and possibly in what sequence, if any, they should be invited, how to avoid dividing lines in Europe, the impact of enlargement on NATO effectiveness continuation of outreach programs with states not invited, and the relationship between NATO and Russia. Of six illustrative alternative future security alignments in Europe (three involving NATO expansion and three not), the first-NATO expansion to include Central and Eastern European states, adding from 1-11 new members, while continuing outreach programs with non-members and establishing a unique relationship with Russia and perhaps Ukraine may be the most supportable.