Purpose: Cognitive development during adolescence affects health long term. We investigated whether level of and change in language-based cognition during adolescence are associated with cognitive performance in midlife. Methods: Participants were enrolled in the Child Health and Development Study and followed during midlife (47–52 years). Adolescent cognition was measured with the Peabody Picture Vocabulary Test at ages 9–11 years (PPVT-9) and 15–17 years (PPVT-15). We examined PPVT-9, as well as a PPVT change score (derived using the standardized regression-based method) in relation to midlife cognition measures of Wechsler Test of Adult Reading, Verbal Fluency, and Digit Symbol tests. Linear regression models were adjusted for childhood socioeconomic status, age, sex, race, and midlife marital status, education, and occupational score. Results: In 357 participants (52.1% female, 25.6% African American), both PPVT-9 (β [95% confidence interval [CI] = 0.26 [0.18, 0.34]) and PPVT change score (β [95% CI] = 2.03 [1.27, 2.80]) were associated with Wechsler Test of Adult Reading at midlife. PPVT-9 was associated with midlife Verbal Fluency (β [95% CI] = 0.18 [0.10, 0.25]), whereas PPVT change score was not (β [95% CI] = −0.01 [−0.68, 0.67]). Neither PPVT-9 nor PPVT change score was associated with midlife Digit Symbol. Conclusions: Both level of and change in language-based cognition during adolescence were associated with midlife vocabulary and language function, even after controlling for midlife occupation and education.