Research suggests that self-esteem can decline in older adulthood. This process could remove a buffer that normally protects individuals against distress-related changes in cortisol secretion. We examined this possibility by testing whether change in self- esteem would predict alterations in cortisol secretion, particularly among older adults who reported high levels of depressive symptoms or perceived stress. 147 older adults (Aged 60+) completed three days of diurnal cortisol measurements at three different time points, namely every two years over a total period of four years. Measures of self-esteem, depressive symptoms, and perceived stress were assessed at T1 and T2. Potential demographic and health-related confounds were measured at baseline (partnership status, SES, mortality risk index, and medication). Linear regression models indicated that a decline in self-esteem from T1 to T2 predicted elevated cortisol output (AUCG) from T2 to T3, F (1, 137) = 8.09, ? = -.25, R2 = .05, p = .005. Interaction analyses revealed that this association was particularly strong among participants who experienced higher T1 or T2 levels of depressive symptoms or perceived stress, +1 SD: ?s = -.34 to -.51, ps < .001, but not significant among their counterparts who reported relatively lower levels of depressive symptoms or perceived stress, -1 SD: ?s = .03 to .11, ps > .43. Declines in self-esteem represent a mechanism that contributes to higher levels of diurnal cortisol secretion if older adults experience psychological distress. Increases in self-esteem, by contrast, can ameliorate older adults� cortisol regulation in stressful circumstances.