In the preparation of this little book I have utilized considerable material written by me for other purposes. Generous use has also been made of the Secondary Division Leaflets of the International Sunday School Association. A deep debt of gratitude is mine to the members of the International Secondary Committee: Messrs. E.H. Nichols, Frank L. Brown, Eugene C. Foster, William C. Johnston, William H. Danforth, S.F. Shattuck, R.A. Waite, Mrs. M.S. Lamoreaux, and the Misses Minnie E. Kennedy, Anna Branch Binford and Helen Gill Lovett, for their great help and counsel in preparing the above leaflets. Grateful acknowledgment is also made to Miss Margaret Slattery, Mrs. J.W. Barnes, Rev. Charles D. Bulla, D.D., Rev. William E. Chalmers, B.D., Rev. C.H. Hubbell, D.D., Rev. A.L. Phillips, D.D., Rev. J.C. Robertson, B.D., and the Rev. R.P. Shepherd, Ph.D., for their advice and suggestions as members of the Committee on Young People's Work of the Sunday School Council of Evangelical Denominations. The plans and methods of these leaflets have the approval of the denominational and interdenominational leaders of North America. I wish, also, to make public mention of the great assistance that Mr. Preston G. Orwig and my colleague, Rev. William A. Brown, have rendered me in the practical working out of many of the methods contained in this volume. Two articles written for the "Boys' Work" volume of the Men and Religion Messages, and one for "Making Religion Efficient" have been modified somewhat for this present work. The aim has been to set forth as completely as possible the relationship of the Sunday school and the boy of the teen years in the light of the genius of the Sunday school. No attempt has been made in this volume to discuss the boy psychologically or otherwise. This has been done so often that the subject has become matter-of-fact. My little volume on "Boy Training," so generously shared in by other writers who are authorities on their subjects, may be referred to for information of this sort. "The Sunday School and the Teens" will, likewise, afford valuable technical information about the Sunday school, it being the report of the International Commission on Adolescence. This book is largely a volume of method and suggestion for leaders and teachers in the Sunday school, to promote the better handling of the so-called boy problem; for the Sunday school must solve the problem of getting and holding the teen age boy, if growth and development are to mark its future progress. Of the approximately ten million teen age boys in the field of the International Sunday School Association, ninety per cent are not now reached by the Sunday school. Of the five per cent enrolled (less than 1,500,000) seventy-five per cent are dropping from its membership. Every village, town and city contributes its share toward this unwarranted leakage. The problem is a universal one.