The administrative and procedural records of the First and Second Dáileanna help tell the story of the early Dáil and its Ministries.
Over the course of its lifetime the First Dáil held 12 sessions that were spread out over 21 days. The Constitution of the Dáil, as approved at its first meeting on 21 January 1919, vested legislative powers in Dáil Éireann and conferred executive powers to a Ministry (Aireacht). This was the settled framework of the British cabinet system, and it has remained the basis of parliamentary government in Ireland until the present day. The modern system of governmental departments grew out of this cabinet system.
Under the Constitution, the Ministry was appointed by, and answerable to, the Dáil. It was headed by a Príomh Aire (more commonly known as the President of Dáil Éireann) who was elected by the Dáil. It contained four Ministers, who were nominated by the President and ratified by the Dáil. The President and Ministers had to be members of the Dáil and they could be removed from office, either individually or collectively, by a parliamentary vote. The President could also dismiss a Minister at any time, while the resignation of the President resulted in the automatic dissolution of the entire Ministry.
The First Ministry was appointed on 22 January 1919. Cathal Brugha was elected President of the Ministry and four Ministers were appointed: Eoin MacNeill (Finance), Michael Collins (Home Affairs), Count Plunkett (Foreign Affairs) and Richard Mulcahy (National Defence). This First Ministry was only intended as a temporary cabinet pending the release of Eamon de Valera from prison. As President of Sinn Féin, de Valera was the natural choice for President of Dáil Éireann.