This document discusses research on the relationship between learner personality traits of introversion/extroversion and second language acquisition. It describes key dimensions of personality including introversion/extroversion. Introverts prefer solitary activities while extroverts enjoy social interaction. Studies have looked at how these traits may affect acquiring basic interpersonal skills versus cognitive academic skills, but the research provides no clear support for these hypotheses. Better research designs are suggested to explore how personality interacts with learning under different instructional conditions.