This book examines the nature of age as an aspect of social identity and its relationship to experiences of formal education. Providing a new and critical approach to debates about age and social identity, the author explores why age remains such an important aspect of self-making in contemporary society. Through an ethnographic account of a secondary school in the south-east of England, the author poses three principal questions. Why are schools in English organised according to age? How do pupils and teachers learn to ‘act their age’ while at school? Ultimately, why does age remain such an important and complex organising concept for modern society? Cutting across lines of class and gender, this timely book will be of interest to students and scholars of self-making and identity in educational contexts, and others interested in how schooling socialises young people into categories of age as the foundational building blocks of modern society.