This study examined the longitudinal implications in late adolescence and emerging adulthood of Openness to Experience measured in preschool in a sample of 102 participants who were followed from preschool through emerging adulthood (age 23). Although gender differences in mean Openness scores were not found, the postpubertal longitudinal correlations associated with preschool Openness differed markedly for the sexes. Preschool boys who received high Openness scores were consistently described, both by self and others, as resilient, competent, and self-assured in young adulthood. In contrast, female participants who received high Openness scores continued to be seen as open at ages 18 and 23 but were also viewed, both by self and others, as more psychologically vulnerable than were their male peers. The discussion focuses on transformations in female development and the different longitudinal implications of Openness to Experience in males and females. (Contains 2 tables and 5 footnotes.)