This article is a review of current research on the risk and protective factors of online gambling among adults. The authors included 42 studies in this review. The selected studies compared 1) people who gambled online to those who gambled offline, or (2) people experiencing problem gambling who gambled online to those not experiencing problem gambling who gambled online. This review is important because it identifies risk and protective factors. These factors could be incorporated in preventive interventions aimed at people who gamble online.