Abstract
This chapter considers the ways in which backbench Members of Parliament (MPs) and peers campaign to change laws and government policies. Policy and legislative campaigning is often conducted by groups of MPs and peers who work together across party lines. Such groupings are commonly supported by external pressure groups, who help to keep the parliamentarians informed on the issue, and who can also provide resources to support campaigning activities. MPs and peers also coordinate their parliamentary activities with lobbying by their pressure group partners. The chapter first examines traditional assumptions about influencing government before turning to actors involved in campaigning to change law and policy. It also describes the formal parliamentary tools as well as informal means employed by backbenchers who campaign for policy or legislative change, along with contemporary developments regarding such activity.