Walter Hallstein becomes President of the first EEC Commission (later European Commission historiography treats this as the first Commission presidency). The College’s early work helped establish the Commission’s role as an executive and initiator of European integration policies.
The Commission holds its first formal meeting at the Château of Val-Duchesse near Brussels, marking the practical start of day-to-day Commission governance for the EEC.
The Treaty establishing a Single Council and a Single Commission is signed in Brussels, setting the legal basis to merge the separate executive bodies of the ECSC, EEC and Euratom into one Commission.
The Merger Treaty takes effect, formally creating a Single Commission and Single Council for the European Communities—an important governance reform simplifying the Communities’ executive structure.
The Rey Commission takes office and becomes the first Commission of the merged European Communities, reflecting the institutional consolidation begun by the Merger Treaty.
Franco Maria Malfatti becomes Commission President, leading the institution during a period that included steps toward deeper integration and the opening of enlargement talks.
Sicco Mansholt becomes Commission President, heading a short-lived Commission that nonetheless coincided with key integration and enlargement developments.
François-Xavier Ortoli becomes Commission President as the Communities begin operating with newly enlarged membership (UK, Ireland, Denmark joined at the start of 1973), increasing the scale and complexity of Commission governance.
Roy Jenkins becomes Commission President; his presidency is commonly associated with renewed work on monetary cooperation, including developments leading toward the European Monetary System.
Gaston Thorn becomes Commission President, leading during a period often characterized by institutional and political difficulties and debates over budget contributions and enlargement pacing.
Jacques Delors becomes Commission President, beginning a decade-long presidency (across three Commissions) widely associated with major momentum for integration, including groundwork for the Single Market and later EMU steps.
The Treaty on European Union (Maastricht) takes effect, reshaping EU governance and strengthening the European Parliament’s powers (including co-decision) and the institutional setting in which the Commission operates.
Jacques Santer becomes Commission President. In the post-Maastricht era, the Commission’s political accountability to the European Parliament became more salient, with the Commission operating under intensifying parliamentary scrutiny.
The Commission resigns collectively amid crisis over allegations of mismanagement and accountability, a watershed moment that accelerated subsequent administrative and governance reforms and underscored Parliament’s growing leverage.
Romano Prodi’s Commission begins its mandate after the Santer resignation, tasked with restoring institutional credibility and steering the Commission through the run-up to major enlargement.
José Manuel Barroso takes office as Commission President, serving two consecutive Commissions during a period that included institutional debates and multiple EU accessions.
The Treaty of Lisbon takes effect, reforming EU governance and the Commission’s institutional context—e.g., establishing the High Representative as a Commission Vice-President and changing rules on the Commission’s size (with a mechanism allowing retention of one Commissioner per member state).
Jean-Claude Juncker becomes Commission President, launching a new College (2014–2019) with an internal organization that prominently used Vice-Presidents to coordinate clusters of policy priorities.
Ursula von der Leyen becomes the first woman to serve as Commission President, and her College takes office for the 2019–2024 mandate.
The European Parliament votes to grant Ursula von der Leyen a second term as Commission President following the 2024 European elections, setting the stage for the next Commission mandate.
European Commission: major institutional reforms and presidencies (1958–2024)
