This thesis examines the use of Facebook as a campaign tool by British political parties over the last decade. The thesis measures and conceptualises party approaches to Facebook, through examining extracted Facebook posts (n=49,551), hand-coded Facebook posts (code n=882, posts n=1481), Facebook Audience Insights and survey data. The thesis finds that the two major parties’ campaigns are defined by a traditional Facebook campaign, alongside a subsidiary new methods Facebook campaign. This use of different pages for different audiences is defined as Janus-faced campaigning. Overall, the thesis argues that Facebook is centrally used for the digital recreation of a traditional offline campaign. Information provision is far more central than participation content, with participation content (if seen) focused on engagement, registering to vote and voting. Although Facebook is showing evolution rather than revolution for party campaigns, the platform offers enhanced abilities for recreating tried and tested traditional campaign methods. Facebook has abilities for superior campaign content such as video, while parties have generated larger more representative virtual memberships (than official memberships) that can be used to campaign to Facebook’s broad audience base. Facebook has given political parties a powerful broadcast tool that bridges the digital and physical doorstep, where social context allows for enhanced message impact. Thus, it is in the mainstream use of Facebook that we likely see its potential electoral impacts. Although the central approach seen by parties is via recreation of a traditional campaign, satellite pages are also examined through the study of Momentum. Satellite campaigns are found to offer parties the ability to campaign in more adventurous ways without threatening their traditional Facebook campaign. Momentum during the 2017 General Election campaigned in a more radical way, including a very strong focus on participation, partisan viral content and using virtual members like official members. This approach offered Labour the best of both worlds. Finally, permanent campaigning is conceptualised and then examined through Momentum’s content across 2018. The page shifted towards an internal campaign role showing how parties can use Facebook in a partisan marshalling role outside of elections.