A supporter of the American rebellion and advocate of radical ideas on religion, philosophy, education, law, medicine, and politics, John Jebb (1736-1786) provides an ideal case to examine the nature of radicalism in 18th-century Britain. Jebb began his career as a clergyman and academic at Cambridge in the 1760s and died as a doctor and leading figure among political reformers in Enlightenment London. Profoundly influenced by David Hartley's attempt to combine a Christian theology of universal salvation with a materialist and determinist account of the mind, Jebb's philosophical and religious radicalism inspired him to work tirelessly for reform. This is the first modern extended study of his life.While at Cambridge, Jebb provoked strong conservative opposition to his religious views and proposals for academic reform. Increasingly marginalized in church and university, as a tide of loyalism swept the country in response to rebellion in America, Jebb resigned as a clergyman and moved to London to work as a doctor. As the American war dragged on with no end in sight, a popular movement urging political reform developed. Jebb became a leader of this movement and was instrumental in establishing a platform that called for universal suffrage and annual elections. British radicals would continue to campaign for this platform until the mid-19th century.