In western Europe, France, Germany, Spain, Italy and Portugal are members of the Schengen area. Denmark, Norway, Sweden, Finland and Iceland are the northern Schengen states. Poland, the Czech Republic, Estonia, Latvia and Hungary are eastern European members. Greece, Romania, Belgium, Liechtenstein and Switzerland are also members of the Schengen area. Slovakia, Luxembourg, Malta and Lithuania have also signed the Schengen Agreement, making them member states.
Five of the 10 EU member states signed the Schengen Agreement on June 14, 1985. Of the 26 members of the Schengen area, four are not members of the European Union: Iceland, Norway, Liechtenstein and Switzerland. England and Ireland decided to opt out of the open borders created by the Schengen Agreement.
Thought they are EU members, Bulgaria, Croatia, Cyprus and Romania have not joined the agreement. Their EU membership obligates them to join in the future.
European microstates such as Andorra, Monaco, Vatican City and San Marino are not members of the Schengen area. However, since they are entirely bordered by Schengen states, it makes them de facto members of the agreement.
In 2015 Hungary threatened to veto Croatia's accession to the Schengen Area due to Croatia's aid to Syrian immigrants seeking asylum in Europe.