This chapter looks specifically at the UK Parliament as this is the central institution of the UK political system. It describes the people in Parliament, its internal makeup, and the way in which it is changing. The chapter examines the roles of members of the House of Commons and House of Lords. It considers the four basic functions of Parliament: providing a basis of government, holding government to account, producing legislation, and interacting with the wider public. The chapter describes three practical examples to help illustrate some of its themes. These are the following: the 2010–15 coalition government’s attempts to reform the House of Lords; the 2009 Wright Committee proposals for parliamentary reform and their implementation; and the practice of pre-appointed hearings conducted by parliamentary committees.