Thomas Ravenscroft is best-known as a composer of rounds owing to his three published collections: Pammelia and Deuteromelia (both 1609), and Melismata (1611), in addition to his harmonizations of the Whole Book of Psalmes (1621) and his original sacred works. A theorist, composer and editor, Ravenscroft wrote two treatises on music theory: A Briefe Discourse (1614), and 'A Treatise of Practicall Musicke' (c.1607), which remains in manuscript. This is the first book to bring together both theoretical works by this important Jacobean musician and to provide critical studies and transcriptions of these treatises.