FIG. 7.—District 6. Well-to-do population. Mixed American. ] In District VI are included 1,400 individuals belonging to the well-to-do and moderately wealthy families of Brookline. The six districts may be considered as representative of the various strata of society, so that we are enabled to study the influenza and its mode of action under varying environment. We have selected areas in the city consisting of households or homes rather than boarding houses and rooming populations. After a few attempts in the latter group we became convinced that the information obtained in rooming houses was utterly valueless. In the Jewish districts we were able, through the kind co-operation of the Federated Jewish Charities, to use trained Jewish Social Service Workers, each of whom had previously worked in the district assigned to her, thereby possessing the confidence of the inhabitants. They were also able to speak the language. One-half of the Italian district was surveyed by an Italian physician and the other half by an American Social Service Worker who knew the Italian language. The information obtained was recorded on printed forms, which were filled out in accordance with detailed written instructions. Form “A” contained the necessary information concerning the family as a whole, including statistical data of each individual, description of the dwelling, of the sanitary condition, of the economic status, etc. Form “B” was filled out for each individual and gave detailed information as to the occupation and illnesses during the 1918–19 or the 1920 influenza epidemics, or during the interval. Form “B” was so arranged that the inspector was not called upon to make the diagnosis of influenza, but to record the various symptoms as described by the patient. The decision as to the diagnosis was made later, by the author. All blank spaces were filled in with either a positive or negative answer, so that the reviewer knew that all questions had been asked and answered. (See Appendix.) The inspection was begun on February 9th, at the height of the epidemic. All records were turned in and reviewed by the author, who blue-penciled obvious inaccuracies and incorporated directions and questions in those instances where he desired further information. The records were then returned to the inspectors who, at the termination of the epidemic early in March, surveyed the entire 10,000 a second time, checking up their first record, correcting any inaccuracies, and adding records of additional cases of influenza which had occurred in the interval. The most careful statistical surveys and compilations are not without error. We have gone into considerable detail in the preceding description in order to demonstrate the several checks that have been made upon the work, without which information others would be unable to judge of the accuracy or value of our work.