Thomas Szasz is a pioneering critic of the psychiatric establishment and a leading libertarian thinker. His many books include <em>The Myth of Mental Illness</em>, <em>Ceremonial Chemistry: The Ritual Persecution of Drugs</em>, <em>Addicts, and Pushers, and The Therapeutic State</em>. In this lecture he will draw on his most recent book, <em>Liberation by Oppression: A Comparative Study of Slavery and Psychiatry</em>, and his work in progress, <em>Faith in Freedom: Libertarian Principles and Psychiatric Practices</em>, to argue that the greatest and most immediate domestic threat to individual liberty is psychiatry. He will show why this is the case, discuss how this situation came into being, and consider the diverse libertarian responses to it.