This book is open access under a CC BY 4.0 license. This book investigates the reasons behind the 2017 youthquake - which saw the highest rate of youth turnout in a quarter of a century, and an unprecedented gap in youth support for Labour over the Conservative Party - from both a comparative and a theoretical perspective. It compares youth turnout and party allegiance over time and traces changes in youth political participation in the UK since the onset of the 2008 global financial crisis - from austerity, to the 2016 EU referendum, to the rise of Corbyn - up until the June 2017 General Election.