On the expulsion of the Rump Parliament on 20 April 1653 by Oliver Cromwell, lord general of the army, supreme power in the nation rested with Cromwell himself. An assembly was called which first met in July, and which adopted the title of parliament, even though none of its members was elected. It began life as a radical assembly, which pursued reforming legislation of which Cromwell at that point in his career approved. Its title comes from the surname of one of its members who represented London, even though he played no particularly significant role in its proceedings. After a short while, it became evident that the membership of this parliament had become more divided politically than Cromwell and his advisers had anticipated, and on 12 December, a majority of the members surrendered their authority to Cromwell, who immediately put in hand plans to inaugurate a protectorate.
At the time of the summoning of the Barebones Parliament, Cromwell was sympathetic to the optimism of those radical protestants in political life known as millenarians. They believed that the creation of a commonwealth in which godly values prevailed was possible, and Cromwell was open to the suggestion that difficulties with earlier parliaments could be overcome if the members were hand-picked instead of being sent to Westminster by the usual uncertainties of parliamentary elections. Some members were recommended by ‘gathered’ congregations, that is, churches which appointed their own ministers and managed their own affairs; others were known to the council which advised Cromwell; others were recommended by senior army officers. Each member received a summons to appear at Westminster in the name of Cromwell as lord general. At its inauguration on 4 July, the members listened to a high-flown speech by Cromwell which encouraged the members to initiate reform and which contrasted the hopes for this assembly with the disappointments of previous parliaments, set against the background of the traumatic events of civil war and revolution.
This Parliament has been called by various titles. The member whose name has provided the popular title was Praisegod Barebone or Barbon, a member of the London Company of Leathersellers. Despite the contemporary name of 'Praisegod' bestowed on him, he consistently signed his name 'Praise Barbone'. He was a religious radical who, though not an ordained clergyman, was an active preacher and leader of a gathered congregation in London. His singular name provided an obvious focus for the ridicule that royalists and conservatives of other kinds heaped on the assembly. A variant of the epithet 'Barebones Parliament' is 'Barebone's Parliament', but the least prejudiced and most accurate title is 'the Nominated Assembly'.
Apart from the way in which it was summoned not elected, another peculiarity of this Parliament was that members were summoned to represent constituencies called 'Scotland', 'Ireland' and 'Wales'