The following study is an attempt to delineate the life and work of John Glas (1695-1773). and to trace the origins, early development, and effects of the religious movement which he initiated. As far as is known to the present writer, no extended treatment of Glas's career, teaching, and movement, has hitherto been offered. The fullest account of Glas consists Of a series of six articles which first appeared in "The Theological Repository" (Liverpool), N. 6., Vol- 111 (1807), the writer of which was probably William Jones, the editor of that periodical. With the exception of the last article, this material was substantially reproduced in the memoirs prefixed respectively to an edition (1813) of Glas's "The Testimony of the King of Martyrs", and to the second edition (1828) of his "The Rise and Progress of the Controversy about the National Covenants". In recent times interesting outlines have been contributed to the "Dictionary of National Biography" by the Rev. Alexander Gordon., and to the "Encyclopaedia of Religion and Ethics" and the "Encyclopaedia brittanica" (11th edition) by the Rev. Dugald Macfadyen, but these are necessarily limited in their scope. One reason why more attention has not been given to the Glasite movement is that the Glasites., acting on their principle of avoiding publicity, have maintained an attitude of reserve respenting their own history. The present, writer however, has gratefully to acknowledge much valuable help and personal kind- ness from Elders, members, and adherents of the Glasite connection He has, visited the four remaining Glasite or Sandemanian, churches In Edinburgh, Glasgow,, and London., as well as the homes of Glasite friends in these cities, Dundee, Perth, and elsewhere. Many manuscripts and letters, including several in the hand-writing of Glass Sandeman, and other leaders in Britain and America,, have been carefully preserved. These have been readily placed at the writer's service and have provided invaluable material for a reconsideration, of the personality and influence of Jobn Glas. The method of treatment adopted is, as follows: - Part 1 covers the period of Glas's life and labours, with special attention to the origin of the controversy in which he was Involved;, the process against Glas in the Church Courts, re- sulting in his deposition from the ministry of the Church of Scotland; and his. later ministry among the churches which arose from his teaching and witness. An attempt is also made to summarise the character of Glas as preacher, scholar, and man. Part II. deals with the distinctive teaching of Glas in relation to Christian Salvation, the Nature and Constitution of the Church, and to Christian Practice. Part III. seeks to show the causes and effects of Glas's movement in its extension beyond Scotland, particularly In England, Wales,, and America., Part IV, contains a brief evaluation or the Glasite movement, indicating its relation to the times, Its influence on contemporary thought,, its theological limitations, and the reasons of Its decline* The Appendix contains a review of the influence of Glas's teaching and movement upon other religious bodies which, though having no direct connection with his Commmion, absorbed various elements of his theology and preserved certain features of the Glasite church order. The churches which sprang directly from Glas's movement are sometimes denominated "Glasite" and at other times "Sandemanlan"-