This study examined the effect of warmth, gregariousness, and positive emotion of extraversion's subvariables on adjustment to college. A survey was conducted on 130 college students with questions on adjustment to college, extraversion, and social support. The results revealed that warmth, gregariousness, positive emotion, and social support significantly correlated with adjustment to college. However, when social support was mediated only warmth and positive emotion predicted adjustment to college. The results of this study are significant for discovering that warmth and positive emotion among many characteristics of extraversion affect adjustment to college, and for the mediating effect of social support. The implication of the results and suggestions for further research are discussed.