Globalization has seen the emergence of virtual teams solving complex organisational problems using computer-mediated technologies. By extending Media Richness Theory, it was the aim of this research to demonstrate that virtual teams can utilise a lean medium, such as email, for effectively solving an equivocal problem, given that participants develop a shared-social construction. A quantitative study was carried out to measure the effects of a shared basis on perceptions of Media Richness, Group Cohesion and Decision-Making Effectiveness of participants engaged in group communication using only email to facilitate their discussions. There was found to be no significant effects of a shared basis on these variables, however, it was found that Media Richness and Group Cohesion have a mediating effect on Decision-Making Effectiveness. In addition to this, the scales used in data collection were, for what is believed to be the first time, exposed to confirmatory factor analysis.