The effect of social networking site (SNS) use on mental health has attracted growing scholarly attention, yet the nature of this relationship remains contentious. A systematic review was conducted to examine mental health outcomes associated specifically with the SNS, Facebook. A total of 65 articles met the inclusion criteria and were included in the review. Facebook use was associated with six key mental health domains: Facebook addiction, anxiety, depression, body image and disordered eating, drinking cognitions and alcohol use, and other mental health problems, albeit the strength and validity of these relationships varied. The review highlighted the multidimensional nature of Facebook use, and the subsequent importance of assessing specific SNS platforms or similar functions over platforms. The application of meta-analytic techniques is required to quantify the nature and direction of the relationships between Facebook use and mental health outcomes, as well as to identify pertinent moderators and individual difference factors.