This quantitative correlational predictive study aims to determine if and to what extent core self-evaluations (CSE), grit, and age, combined and individually predict generalized expectancy for success (GES) in adults ages 18–65 in the United States. The sample size was 115. The theoretical foundation was the CSE Theory and the Grit Model. The instruments used for the study were CSE, Grit-S, and GESS-R Scales. The Grit-S and GESS-R had a high level of reliability with Cronbach’s alpha of .72 and .89, respectively. CSE showed a Cronbach’s alpha of .68. Multiple linear regression analysis was performed to measure the predictive relationship between CSE, grit, and age combined and individually, and generalized expectancy for success (GES). The results for CSE, grit, and age combined showed statistically significant results F(3,111) = 27.56, p < .001, CSE showed a direct predictive relationship with GES (ß = .404, t = 4.940, p < .001), and grit showed an inverse predictive relationship with GES (β = − .360, t = -4.366, p < .001). The relationship was negative because GES decreased as grit increased. Age did not show statistically significant results (ß = − .063, t = − .866, p = .388), and the null hypothesis was maintained. The results of this study contribute to the literature on CSE, grit, and generalized expectancy for success.