Anonymity, an important feature of computer-mediated communication (CMC), is embedded in this new technology. With the penetration of the Internet in society, many daily activities involve online interactions. Anonymity affects both the task and social aspects of online communication including information exchange, decision making, and relationship development. This review examines the effects of anonymity on human behavior. It outlines how the prior literature has attempted to address this issue and how the Social Identity Deindividuation (SIDE) model has developed as an attempt to tackle this question. More importantly, it discusses a framework describing the multidimensions of anonymity in CMC [1], and subsequently raised five propositions inspired by this framework. Furthermore, using McLeod’s framework, this review evaluates SIDE studies with regard to their anonymity manipulations. This critique reveals possible future research directions for refining the SIDE model and better studying the effect of anonymity in virtual environment.