The current study is among the first to examine rank-order stability and mean-level change across college in both broad Big Five personality trait domains (e.g., Neuroticism) and the narrower facets underlying these domains (i.e., self-reproach, anxiety, and depression). In addition, the current study tests longitudinal associations between Big Five domains and facets and 3 aspects of adjustment: self-esteem, academic adjustment, and social adjustment in college. Specifically, the study examines codevelopment (correlated change), personality effects on later changes in adjustment, and adjustment effects on later changes in personality. Two large longitudinal samples from different countries were employed. Results suggested that rank-order stabilities of facets were generally large (i.e., >.50) across samples, and comparable with those observed for trait domains. Mean-level findings were largely in line with the maturity principle: levels of neuroticism and (most of) its facets decreased, whereas levels of the other domains and facets were either stable or increased. However, patterns sometimes slightly differed between facets of the same trait domain. All 3 types of longitudinal associations between personality and adjustment were found, but unlike mean-level change often varied by facet. The Extraversion facet of positive affect and the Conscientiousness facets of goal-striving and dependability were positively associated with all 3 adjustment indicators in both samples, whereas the Neuroticism facets of depression and self-reproach were consistently negatively associated with adjustment. In sum, our findings demonstrate that considering Big Five trait facets may be useful to reveal the nuanced ways in which personality develops in tandem with adjustment in college.