Introduction. The scope of the problem: Treatises (in MS and in print) containing the rudiments of music and/or the theory of composition, from the end of the 16th century to the beginning of the 18th century. For purposes of comparison, the 17th century French theorists' works are examined; though they are fewer, and on the whole, they lagged behind their English contemporaries. Review of background literature. Part I. Chap. I. Title-page details of each treatise, and a brief account of the work and its writer. Chap. II. A survey of Playford's "Introduction to the Skill of Musick", which ran to 22 separate issues from 1654 to 1730. How the book developed and what additions and alterations were made. The 1694 edition, revised by Henry Purcell, is particularly interesting. Chap. III. An examination of the proposed musical reforms contained in Thomas Salmon's "Essay" (1672); and the arguments between Salmon and Matthew Locke. Part II. Chap. IV. The rudiments of music. Chap. V. The theory of composition. Part II comprises a concordance of the major subjects included in the different treatises, (e.g. the Gamut, Ligatures, False Relation, Cadences, etc.). The development of each subject is traced; plagiarisms observed; and rules and examples compared, analysed and criticised. Part III. Chap. V. Gresham College, London: source of instruction in the theory of music. An account of the 17th century music professors; the type of audience; and the lectures given. Chap. VI. The social significance of the 17th century treatises. The theorists writing for a wide audience: budding composers, amateurs, young practitioners, music lovers, those unable to procure personal tuition, etc. The popularity of the small compendium: inexpensive, "plain and easy"; a means of self-tuition. The prestige of music in the 17th century; the interest taken in theory and composition. Political, social and religious influences on musical developments. Appendices. Annotated copies of Ravenscroft's MS Treatise, and Dr. Blow's "Rules for Composition".