The purpose of this study is to examine whether anger experiences and expressions mediate the effects of anger rumination on student adaptation to college. The subjects for this study were recruited from three universities in Seoul and the Gyeong-gi area. A total of 499 college students volunteered to participate in this study. 54 of the participants were excluded due to insufficient responses or non-responses; as such, a total of 445 (male: 160, female, 285) college students’ data was collected for this study. The Korean version of the anger rumination scale (K-ARS), the Korean version of the State-Trait Anger Expression inventory (STAXI-K), Student Adjustment to College Questionnaire (SACQ) was completed; SPSS 21.0 and SPSS Process Macro programs were used to analyze the collected data. The data yielded two main findings. First, anger rumination, state anger, trait anger, anger-in, and anger-out were negatively correlated with adaption to college life while self-oriented perfectionism was positively correlated with academic adaptation, and anger-control was positively correlated with students’ college life adaptation. Second, the study found that the higher the rumination of anger memory and the rumination of revenge, the more difficult the students’ adaptation to college life; rumination of anger memory and thoughts of revenge tracked through state anger and anger-in, and this procedure impeded adaptation. On the other hand, rumination of cause was positively associated with anger-control, which enhanced students’ adaptation to college life. The present study verified that the focus of anger rumination determines its effects, whether they are positive and negative. In the effects of anger rumination on college life adaptation, state anger, anger-in, and anger-control showed mediation effects. The results here can be expected to be instrumental in the field of education, counseling, and treatment programs for college life adaptation.