The relative effectiveness of three communications media is examined by applying social presence theory. The three media: Face-To-Face Interaction (FTF), Instant Messaging (IM), and Email (EM) – are conceptualized to have different levels of social presence. Their impact on the buyer-seller negotiation processes, such as problem solving bargaining strategies, and negotiation outcomes, such as negotiation time, joint profit, and joint satisfaction were examined using negotiation simulations conducted in FTF, IM, and EM conditions. Participants completed questionnaires after negotiating in one of the three conditions. The central finding of the study is that higher social presence in the individualistically conditioned negotiation simulations caused more time spent, and lower joint satisfaction for negotiators.