This chapter is a study of the relationships between Parliament, print and petitioning in revolutionary England. Jason Peacey explores the tension between the potential for political participation at Westminster and the problems related to this practice, and argues that this tension allows for a better understanding of political radicalism in the English Revolution. His essay rests on two foundations: first, the idea that an information revolution relating to Parliament developed in the seventeenth century, which made political information affordable; second, a sense that Parliament was extremely useful, hence citizens’ increased participation in its proceedings, not least through petitioning. Peacey highlights the radicalisation of petitioners’ rhetoric from case studies and argues that that radicalism was forged by forces that brought together disparate individuals whose ideas were shaped by their involvement in participatory politics.