On 9th December 2011, EU and Croatian leaders have signed Croatia's EU Accession Treaty. Subject to the Treaty's ratification by all Member States and Croatia, the country will become the 28th Member State of the European Union on 1 July 2013. The Accession Treaty has been signed by the 27 Heads of State and Government and by the Croatian President and Prime Minister. Following the signature each Member State proceeds now with the ratification of the Treaty in accordance with their national provisions. Croatia has announced that it will hold a referendum on the ratification of the EU accession treaty in early 2012.
During the interim period between the signature of the Accession Treaty and the actual date of accession the work on Croatia's preparations for EU membership continues. Croatia needs to complete the remaining implementation of the commitments taken during the accession negotiations. Through the closing of accession negotiations and by finalising the Accession Treaty, Member States have given a mandate to the European Commission to carefully monitor the progress Croatia is making in all the areas covered. The Accession Treaty includes provisions which allow for appropriate measures to be taken in case problems are identified during the monitoring process.
Until its accession, Croatia will have an active observer status in most of the Council working groups as well as Commission committees. This allows Croatia to become familiar with the working methods of the EU institutions and to become involved in the decision-making process.
More information here, full Treaty available here.
Source europa.eu, Reference: MEMO/11/883