In 2016, the striking electoral success of the UK Vote Leave campaign and Donald Trump's presidential bid defied conventional expectations and transformed the political landscape. Considered together, these two largely unpredicted events constitute a defining moment in the process of the incorporation of far-right populist discourse in mainstream politics. This timely book argues that there has been a change in the fundamental dynamic of the mainstreaming of far-right populist discourse. In recent elections, anti-establishment actors have rewritten the playbook, defeated the establishment and redefined political norms. They have effectively outplayed, overtaken and trumped mainstream parties and policies. As fringe discourse becomes mainstream, how we conceive of the political landscape and indeed the very distinction between a political centre and periphery has been challenged. This book provides new theoretical tools and empirical analyses to understand the ongoing mainstreaming of far-right populism. Offering case studies and comparative research, it analyses recent political events in the US, UK, France and Belgium. This book is essential reading for scholars and students of populism and far-right politics who seek to make sense of recent world-altering events.