How Countries Join the EU—the Long Road to Membership

A Club With a Rigorous Entrance Exam

The European Union has grown from six founding members in 1957 to 27 today, but joining is anything but simple. Every country that has entered the bloc has navigated a multi-year gauntlet of political reform, legal alignment, and diplomatic negotiation. The process is designed to ensure that new members can fully participate in—and strengthen—the world's largest single market and one of its most ambitious political projects.

The Copenhagen Criteria: Setting the Bar

Before a country can even begin negotiations, it must meet the Copenhagen criteria, established by EU leaders in 1993. These require three things: stable institutions guaranteeing democracy, rule of law, and human rights; a functioning market economy capable of competing within the EU's single market; and the ability to adopt and implement the full body of EU law, known as the acquis communautaire.

The acquis is enormous—roughly 80,000 pages of legislation covering everything from food safety standards to data privacy. Adopting it is the central challenge of membership.

Three Steps From Application to Membership

1. Candidacy

A country submits a formal application to the Council of the European Union. The European Commission then assesses whether the applicant meets the basic criteria and issues a recommendation. Granting candidate status requires a unanimous vote by all existing member states—giving every country an effective veto from the very start.

2. Accession Negotiations

This is the longest and most complex phase. The acquis is divided into 35 negotiating chapters covering policy areas such as free movement of goods, agriculture, competition, energy, and foreign policy. For each chapter, the Commission conducts a detailed screening of the candidate's laws and institutions, identifies gaps, and sets benchmarks for reform.

Chapters are opened and provisionally closed one by one. A single member state can block progress on any chapter. Croatia, which joined in 2013, spent eight years in negotiations. Turkey, which applied in 1987, has been a candidate since 1999 with many chapters still frozen.

3. Treaty Ratification

Once all 35 chapters are closed, the terms are compiled into a Treaty of Accession. This treaty must be approved by the European Parliament, signed by all member-state governments, and ratified by every national parliament—adding yet another potential chokepoint.

Why It Takes So Long

The EU's enlargement history shows just how variable the timeline can be. Austria, Finland, and Sweden joined in 1995 after relatively short negotiations, partly because their economies and legal systems were already closely aligned with EU standards. By contrast, the ten Central and Eastern European countries that joined in the historic 2004 enlargement spent roughly a decade transforming their post-communist institutions to meet the bar.

The unanimity requirement is the process's most powerful brake. Any member state can stall or block a candidacy for political reasons entirely unrelated to the applicant's readiness. This dynamic has played out repeatedly, from France's vetoes of British membership in the 1960s to more recent blockages involving Western Balkan candidates.

Current Candidates and the Road Ahead

The EU currently has several active candidates, including Ukraine, Moldova, and several Western Balkan nations such as Serbia, Montenegro, and Albania. Ukraine received candidate status in June 2022 and began formal negotiations in 2024, but progress depends on both internal reforms and the political will of all 27 existing members.

The accession process remains the EU's primary tool for projecting stability and democratic norms across its neighbourhood. It is slow by design—built on the premise that thorough preparation prevents the governance problems that could undermine the bloc from within. For aspiring members, the road to Brussels is long, but the destination reshapes nations along the way.