Sufism, the name given to Islamic mysticism, has been the subject of many studies, but the orders through which the organizational aspect of the Sufi spirit was expressed have been neglected. Here, author J. Spencer Trimingham offers a clear and detailed account of the formation and development of the Sufi schools and orders (tariqas) from the second century of Islam until modern times. Trimingham focuses on the practical disciplines behind the mystical aspects of Sufism which initially attracted a Western audience. He shows how Sufism developed and changed, traces its relationship to the unfolding and spread of mystical ideas, and describes in sharp detail its rituals and ceremonial practices. Finally, he assesses the influence of these Sufi orders upon Islamic society in general.