Foreword SUCH a survey of this subject as we have been able to make indicates that cases diagnosed as silicosis differ in various communities and even in various industries in the same community. We believe, therefore, that a comprehensive approach to this problem should be based on a study of roentgenologic and pathologic findings observed in various industries and widely separated communities. To those who have aided us in the assembling of this material we wish to give special credit, and to express our sincere appreciation. The list is too long for us to include them as collaborators, but we do wish to mention at the very beginning that without the co-operation of the following men this investigation could not have been completed. Harvey C. Bridgers, M.D., Blue Ridge Summit, Pa. Philip Howard Cook, M.D., Worcester, Mass. William Joseph Corcoran, M.D., Scranton, Pa. Sol Davidson, M.D., Rochester, N. Y. John S. Derr, M.D., Frederick, Md. C. Zent Garber, M.D., New York, N. Y. Leroy Gardner, M.D., Saranac Lake, N. Y. Arial W. George, M.D., Boston, Mass. Omer Grenville Hague, M.D., Winnipeg, Man., Canada. Leonidas B. Harless, M.D., Gauley Bridge, W. Va. Courtenay I. Headland, M.D., Yonkers, N. Y. William G. Herrman, M.D., Asbury Park, N. J. George Holmes, M.D., Boston, Mass. William Kelly, M.D., Middletown, N. Y. Edward Klein, M.D., Perth Amboy, N. J. Harrison Martland, M.D., Newark, N. J. James E. McArthur, M.D., Noranda, Quebec, Canada. Eugene P. Pendergrass, M.D., Philadelphia, Pa. Raphael Pomeranz, M.D., Newark, N. J. Robert E. Pound, M.D., New York, N. Y. Benjamin S. Putts, M.D., Erie, Pa. Walter A. Schmitz, M.D., Middletown, N. Y. Israel Steinberg, M.D., New York, N. Y. Beverly L. Vosburgh, M.D., Schenectady, N. Y. Importance of the Roentgenologic Diagnosis of Pneumoconiosis (Silicosis).—It is almost universally conceded that the diagnosis of pneumoconiosis (silicosis) depends upon the accurate interpretation of satisfactory roentgenograms, preferably stereoscopic ones. The British, in South Africa, early recognized this, and that America agreed with the British was manifested by a report made to the United States Government (1) by a committee of physicians, in which it was stated that “only the physician who has examined the subject, has obtained the occupational history of adequate exposure to silica dust, and has before him a suitable roentgenogram of the chest should make the diagnosis of silicosis.”