Over 80 per cent. of school sickness, whether judged by the number of cases or by the time lost, is transmitted by “droplet” infection. The alleged increase in sickness in public schools is partly apparent, due to increased attention to minor febricula and partly real, due (1) to increased influenza prevalence, the aftermath of the great epidemic of 1918, and (2) to the increased demand for public school education leading to pressure upon accommodation, and especially to overcrowding in dormitories. The bulk of the droplet infections are accounted for by (1) influenza; (2) feverish cold, chill, or P.U.O.; (3) tonsillitis; regular infectious diseases make a comparatively small showing. The incidence and bacteriological findings and the variations in the incidence of pneumonia and otitis media are discussed. Are these complications really secondary epidemics? Tonsillitis, bacteriological findings, milk. Prophylaxis.—Efficacy of vaccines uncertain. Some evidence that they may diminish the onset of complications. If given vaccines should be administered before the danger period, i.e., not later than November. Intensive prophylaxia other than vaccines during the first half of the Lent term would probably amply repay any trouble. It should include:— Special efforts to prevent boys returning to school after the Christmas holidays infected with influenza or febricula. Temperature taking for three weeks. Immediate isolation of all pyrexias and catarrhs. No work before breakfast for at least the first six weeks of the term. All hot baths and showers taken during the day or after games to be followed by cold showers. Prevention of chill in watching games, etc. Increased provision for drying clothes, uniforms and boots. Infection mainly takes place in sleeping quarters, and proper spacing out of beds and thorough “cross” ventilation in dormitories is of paramount importance; instances of cross infection due to proximity of beds; illustrated by bed charts and bacteriological findings; standards of wall space, floor space and cubic space, laid down by the Royal Commission, Board of Education. No school authority has done its duty to its pupils unless it has provided dormitory accommodation allowing at least 3 ft. of clear space between the edges of beds, and thorough and through ventilation. Until these essential wants are met, the provision of properly sited, amply spaced and “cross” ventilated dormitories should take precedence of all other building requirements. Milk should be pasteurized.