This study investigates students' involvement in Facebook® as a course management system (CMS), Facebook acceptance, and the relationships between the two. The study used Facebook as a CMS in two freshman courses and employed mixed method as part of an action-research approach. Forty-two students participated in the study, and 12 of those students were selected for face-to-face interviews through maximum variation sampling. Quantitative data were collected through questionnaires and course Facebook page logs. Qualitative data were collected through the interviews. The quantitative data analysis consisted of descriptive statistics and correlation analyses. The findings indicate that the relationships between course Facebook page involvement and Facebook acceptance differed according to the course. The findings support that Facebook as a CMS has the potential to increase student involvement in discussions and out-of-class communication among instructors and students.