The Interregnum was the period between the execution of Charles I on 30 January 1649 and the arrival of his son Charles II in London on 29 May 1660, which marked the start of the Restoration. During the Interregnum, England was under various forms of republican government.

The politics of the period were dominated by the wishes of the Grandees (senior officers) of the New Model Army and their civilian supporters. They encouraged (or at least tolerated) several republican regimes. From 1649 until 1653 executive powers lay with the Council of State, while legislative functions were carried out by the Rump Parliament.

In 1653, the Grandees, with Oliver Cromwell leading these reformists, dismissed the Rump Parliament, replacing it with a Nominated Assembly (nicknamed the Parliament of Saints or Barebone's Parliament). This Barebone's Parliament was composed of 140 nominees, 129 from England and Wales, five from Scotland and six from Ireland. It proved to be as difficult for the executive to work with this Parliament as it had with the Rump Parliament, so after sitting for five months, members friendly to the Grandees engendered its dissolution on 12 December 1653.

The Instrument of Government was the first written constitution, adopted on 15 December 1653, Cromwell was installed as Lord Protector on the following day. The Instrument of Government granted executive power to the Lord Protector. Although this post was elective, not hereditary, it was to be held for life. It also created a one chamber Parliament with its members chosen from redrawn districts that ultimately favored the gentry and required the calling of triennial Parliaments, with each sitting for at least five months. This would also mark the permanent disenfranchisement of Roman Catholics and all the participants of the Irish Rebellion. In January 1655, Cromwell dissolved the first Protectorate Parliament, ushering in a period of military Rule of the Major-Generals.

The Instruments of Government was replaced in May 1657 by England's second, and last, codified constitution, the Humble Petition and Advice. However Cromwell died the next year, and his nominated successor as Lord Protector, his son Richard, proved unable to govern effectively as various political parties strove to gain power.

The Protectorate came to an end in May 1659 when the Grandees recalled the Rump Parliament, which authorised a Committee of Safety to replace Richard's Council of State. This ushered in a period of unstable government, which did not come to an end until February 1660 when General George Monck, the English military governor of Scotland, marched to London at the head of his troops, and oversaw the restoration of the monarchy under Charles II.

After the Parliamentarian victory in the English Civil War, the Puritan views of the majority of Parliament and its supporters began to be imposed on the rest of the country. The Puritans advocated an austere lifestyle and restricted what they saw as the excesses of the previous regime. Most prominently, holidays such as Christmas and Easter were suppressed. Pastimes such as the theatre and gambling were also banned. However, some forms of art that were thought to be "virtuous", such as opera, were encouraged. These changes are often credited to Cromwell, though they were introduced by the Commonwealth Parliament.

Rabbi Menasseh Ben Israel met Cromwell in 1655 to discuss the admission of Jews into England. Cromwell did not agree to all the rights that Ben Israel requested, but the opening of Jewish synagogues and burial grounds was tolerated under Cromwell's Protectorate. Judaism was still not practised openly in England, since Cromwell's move had been controversial and many in England were still hostile toward Jews. Life for Jews in England improved in that they could no longer be prosecuted if caught worshipping, yet discrimination continued.