The behavioral study determines whether sex differences in stress responses may assist in explaining sex differences in CHD. The ongoing research program has documented differences in psychological responses to acute stress between men and women and among women who vary in reproductive hormone status. Building on these findings, but also departing from previous efforts in strategy and design, five studies are conducted. Study 1 measures hemodynamic measures that underlie sex differences in cardiovascular responses to behavioral challenge. Using longitudinal designs, Study 2 compares women's stress responses prior to and three months after surgical menopause, whereas Study 3 compares healthy women's stress responses prior to and three months after a "temporary menopause" due to the administration of a GnRH agonist. In both studies, some women after the second testing are administered estrogen replacement therapy and stress responses are again measured. Thus, Studies 2 and 3 also address the effects of estrogen replacement therapy on stress responses. These studies gain significance from the fact that surgical menopause is associated with heightened risk for CHD, whereas estrogen replacement therapy is associated with protection from CHD. Study 4 describes the extent of sex differences in exposure to psychological stressors among men and women from two levels of social class. Social class is included in the design because it is a risk factor for psychological stress and for CHD. The final study tests the hypothesis that sex differences in stress responses are attenuated during a task within a feminine area of competency and accentuated during a task within a masculine area of competency.