Social networking sites are changing the way in which young people develop and maintain friendships and relationships. This study investigated the relationship between level of Facebook addiction, Facebook behaviors, gender, and intimacy development in emerging adults. Participants were 273 university students aged 18 to 25. They completed an online questionnaire that measured their level of Facebook addiction, what they do on Facebook, and their ability to form intimate relationships. A gender difference was found with long distance, passive, active photo, and organizing behaviors relating to high levels of Facebook addiction in females, whereas gaming was related to high levels of Facebook addiction in males. Intimacy development was related to high Facebook use and long distance, active photo, and organizing behaviors, but not to the level of Facebook addiction. Implications regarding the identification of at-risk for addiction emerging adults are discussed.