Linking temperament and personality traits from late childhood to adulthood by examining continuity, stability, and change.

Theories of personality development emphasize the continuity between who we are as a child and who we are as an adult. The conceptual overlap in influential trait taxonomies designed for children (Rothbart's temperament model) and adults (the Big Five personality) has reinforced theories about developmental continuity, but key hypotheses remain untested because no studies have linked these trait models longitudinally. To bridge this divide, the present study used longitudinal data from a sample of 674 Mexican-origin youth who completed assessments of Rothbart's temperament traits (i.e., Negative Emotionality, Surgency, Affiliation, Effortful Control) from ages 10 to 16 and assessments of Big Five personality traits from ages 14 to 26. Leveraging two waves of overlapping temperament/personality trait assessments at ages 14 and 16, we found the following: (a) continuity between childhood/adolescent temperament and age 26 personality, with the strongest associations between conceptually similar traits, and Effortful Control predicting all Big Five traits (except Extraversion), suggesting self-regulation broadly promotes maturation; (b) temperament starts predicting adult personality traits by age 12-14, consistent with theory positing the temperamental foundations of adult personality crystallize in adolescence; (c) conceptually similar temperament/personality traits reflect different expressions of the same underlying trait from age 10 to 26, established by latent growth models of joint temperament/personality factors; and (d) mean-level personality development across late childhood to adulthood showing that all joint traits maintain consistent rank-order stability and youth increase in Effortful Control/Conscientiousness, decrease in Negative Emotionality/Neuroticism and Surgency/Extraversion, and do not change in Affiliation/Agreeableness. Findings add novel support for widely accepted-yet largely untested-theories, although some unexpected results undermine prevailing assumptions about personality trait development. (PsycInfo Database Record (c) 2026 APA, all rights reserved).