The Levellers were a political movement active during the Wars of the Three Kingdoms who were committed to popular sovereignty, extended suffrage, equality before the law and religious tolerance. The hallmark of Leveller thought was its populism, as shown by its emphasis on equal natural rights, and their practice of reaching the public through pamphlets, petitions and vocal appeals to the crowd.

A political movement is a collective attempt by a group of people to change government policy or social values. Political movements are usually in opposition to an element of the status quo, and are often associated with a certain ideology. Some theories of political movements are the political opportunity theory, which states that political movements stem from mere circumstances, and the resource mobilization theory which states that political movements result from strategic organization and relevant resources. Political movements are also related to political parties in the sense that they both aim to make an impact on the government and that several political parties have emerged from initial political movements. While political parties are engaged with a multitude of issues, political movements tend to focus on only one major issue.