Major depressive disorder (MDD), generalized anxiety disorder (GAD), and panic disorder (PD), constitute common mental disorders that may have chronic and disabling courses. Cognitive and behavioral theories posit that lack of engagement in certain strategies (goal persistence, self-mastery, positive reappraisal) increases vulnerability toward these disorders. Further, scar effect theories assert that experiencing more of these disorders may diminish engagement in such strategies within individuals across time. However, dynamic longitudinal associations between cognitive-behavioral strategies (CBS) and disorder counts across adulthood are not well understood. Using bivariate latent difference score models, this study aimed to test the dynamic trajectories between disorder counts and each CBS across 18 years. Participants were 3,294 community-dwelling adults ages 45.62 years (SD = 11.41, range = 20-74; 54.61% female) who took part in 3 waves of measurement spaced 9 years apart. Self-mastery, disorder counts, and their change were not significantly related. However, higher within-subject increase in goal persistence (but not self-mastery or positive reappraisal) led to greater future decline in disorder counts, but not vice versa. Last, within individuals, greater prior levels of goal persistence and positive reappraisal predicted larger subsequent reduction in disorder counts, and vice versa. The reciprocal, bidirectional associations between specific CBS (goal persistence, positive reappraisal) and disorder counts support both vulnerability and scar models of depression and anxiety. Treatments for MDD, GAD, and PD should attempt to enhance perseverance and optimism. Theoretical and clinical implications are further discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).