CEFTA

The Central European Free Trade Agreement, or CEFTA, was formed in 1992 by the Visegrád countries - Czechoslovakia, Poland, and Hungary.  After the Velvet Divorce both Czech Republic and Slovakia became independent members.  The purpose was to work together towards integrating political, economic, security, and legal systems with western free-market economies.

Over the years, other countries have joined CEFTA.  However, once a country joins the European Union it must leave CEFTA.  Former members include Bulgaria, Croatia, Romania, and Slovenia.  Basically being a CEFTA member servers as good preparation for eventually joining the EU.

Current CEFTA members

CEFTA seems less "Central Europe" and more "Balkans" to me.  The seven current members are Albania, Bosnia and Herzegovina, Kosovo, Moldova, Montenegro, Macedonia, and Serbia.  Combined the CEFTA countries have a combined population of about 21,5 million people and a GDP over $290 billion.