The study tested the hypothesis that a life-organizational stress of significant proportions typically appears shortly before the onset of TB. The sample comprised of all persons employed at Firland Sanatorium from its establishment at the present location in Seattle, Washington, USA. One group of sanatorium employees who became ill with TB was compared with an individually matched group of employees who remained well. The matching included age, sex, marital status, education, time of employment, job classification, income, skin test reading, appearance of chest roentgenograms, and previous record of certain chronic conditions. Those who became ill had experienced a concentration of disturbances such as domestic strife, residential and occupational changes and, personal crises during the two years preceding the change in a series of quarterly chest films, leading to the determination of pulmonary TB. This concentration of disturbances or situational crises was significant in comparison with the experience of the group of subjects who were well. The TB group also evidenced a significant degree of psychoneurotic pathology and did not recognize or could not admit their personality deficit on questions in which this recognition was obvious. The conclusion appears reasonable that many of the employees who became ill did so in a situation of stress which would be conducive to lowered resistance. Within the acknowledged limitations of the test, the postulation of psychosocial crisis as one of the precipitant causes is tenable.