Studies have shown that vulnerability to disease is a function of psychosocial factors. This study hypothesized that disease onset is antedated by life changes and is influenced by the individual's "behavioral rigidity." The subjects were 160 female college students from three undergraduate general elective courses. An index of life change (LCI) was administered to each subject, presenting descriptions of important pressures and conflicts, with instruction that she indicate which ones she had personally experienced during the past calender year. A test of behavioral rigidity was also administered. Responses to the LCI indicated that low life change subjects reported significantly fewer illnesses than did the high life change subjects. The results supported the hypothesis that life stress plays a significant role in the development of illnesses. Responses to the behavioral rigidity measure and subsequent analysis of the interaction between this variable and life change did not prove to be statistically significant. It should be noted, however, that high flexibility subjects did report fewer illnesses than low flexibility subjects within the low and high life change groups. Additional studies must be undertaken in order to assess the trend found for interaction effects.