Computer-mediated communication (CMC) on the Internet has been claimed to possess a degree of anonymity that makes the gender of online communicators irrelevant or invisible; this purportedly allows women and men to participate and be recognized for their contributions equally, in contrast with patterns of male dominance traditionally observed in face-to-face communication. This chapter surveys research on gender and CMC, including textual, multimodal, and mobile communications, published between 1989 and 2013. The body of evidence taken as a whole runs counter to the claim that gender is invisible or irrelevant in CMC, or that CMC equalizes gender-based power and status differentials. In concluding, the notion of anonymity is critiqued, and the question of difference vs. disparity is addressed.