In 1910 the Secretary of the Interior of the Philippine Islands did me the honor to invite me to accompany him on his annual tour of inspection through the Mountain Province of Northern Luzon. In the follo-wing pages I have tried to describe what fell under my notice during the journey, with such comments, obser-vations, and conclusions as seemed pertinent. I should like here to thank Mr. Worcester for having invited me to join him, and Major-General Duvall, United States Army, for allowing me to accept. My thanks are also due the various officers and officials of the Insular Government who placed me under obli-gations by their hospitality and other courtesies and by the never-failing patience with which they received and answered my many questions. To my friend Colonel J.G. Harbord, United States Army, Assistant Director of Constabulary, I am beholden for instruc-tions sent out in advance of the journey to the various Constabulary posts on the itinerary, directing them to offer me every opportunity to accomplish the purpose of my trip.