This article reports a study undertaken to investigate some of the social psychological processes underlying computer-supported group discussion in natural computer-mediated contexts. Based on the concept of deindividuation, it was hypothesized that personal identifiability and group identity would be important factors that affect the perceptions and behavior of members of computer-mediated groups. The degree of personal identifiability and the strength of group identity were manipulated across groups of geographically dispersed computer users who took part in e-mail discussions during a 2- week period. The results do not support the association between deindividuation and uninhibited behavior cited in much previous research. Instead, the data provide some support for a social identity perspective of computer-mediated communication, which explains the higher levels uninhibited in identifiable computer-mediated groups. However, predictions based on social identity theory regarding group polarization and group cohesion were not supported. Possible explanations for this are discussed and further research is suggested to resolve these discrepancies.