Because of the prevalence of mobile devices, the overuse of social networking sites has become a global phenomenon. One of the most popular social networking sites, Facebook, has received a considerable attention in recent years, and the excessive use of Facebook has become a major concern in schools. The purpose of this study was to investigate the reasons for Facebook addiction. By surveying 894 college students in Taiwan, we found that although only 1% was classified as addicts, 17.8% were in the alert group. Approximately 80% of the students used Facebook every day, and 10% spent more than 8 h a day on Facebook. Interpersonal relationships and online social support were found to be positively associated with Facebook addiction; however, some personality traits, such as agreeableness, conscientiousness, and neuroticism, were negatively associated with Facebook addiction. Online interpersonal relationships and neuroticism were found to be prominent predictors of Facebook addiction. Practical implications are provided herein.