This book explores how Parliament managed the upbringing of King Charles I's two youngest children - Henry, Duke of Gloucester (1640-1660) and Princess Elizabeth (1635-1650) - during the course and aftermath of the English Civil War. It presents their household, their education and their religious formation as extensions of Parliamentarian political agenda to control the monarchy, and examines portrayals and perceptions of the junior princes, especially Elizabeth, from different political factions during the war and post-war peace negotiations. Spanning from the beginning of their custody at the outbreak of civil war in 1642, and including the two years of James, Duke of York's imprisonment, this book charts their political significance to the fledgling Commonwealth up until Henry of Gloucester's departure in 1653. Exploring the impact of the regicide on the children's usefulness to the new republic, as well as how their experience and agency effected the adult agendas around them, Underwood shows how upbringing was key to parliament's interest in the princes as their political usefulness depended on the kind of adults they would become. This study is a history both of childhood and of the politics of childhood in England's turbulent Seventeenth Century.