This paper examines changing strategies of isolation in the New York Hospital between 1771 and 1930 by correlating the facilities available for isolation with changing reactions to internal disease incidence, changing medical rules and regulations, and shifting ward categories. To prevent internal "epidemics" of telltale diseases such as erysipelas, pyemia, and "hospital gangrene," what (or who) was isolated from what, and how that isolation was achieved, altered drastically. Traditional strategies of increasing the air space and flow around each patient gave way to Florence Nightingale's sanitary nursing, Joseph Lister's antisepsis, Joseph Grancher's barrier system of nursing, D. L. Richardson's aseptic nursing, and Charles Chapin's advocacy of individual cubicles. The larger social and medical transformations of the hospital colored all of these shifts. But the changing isolation strategies also reveal a transformation of the underlying understanding of the role that hospital architecture played in disease incidence.