This book examines how parties voice voter preferences in plenary debates—an often-overlooked dimension of parliamentary politics. Combining theoretical insights with an innovative process model of representation, the book empirically tests how party positions shift between elections and legislative action. Using machine learning to analyse manifestos and speeches, it provides new data and methods for assessing substantive representation. This work will appeal to theorists of representation, comparativists exploring party competition and legislative behaviour, and methodologists employing text-as-data approaches in political research.