Voting tools in Group Support Systems (GSS) have been considered valuable assets in groups’ decision processes. One important aspect of voting is the method of conducting the vote. Research in Social Choice Theory (SCT) has shown that different voting methods can lead to different voting outcomes. However, SCT seldom addresses how a voting method affects decision making processes. Voting methods interacting with the computation power and communication capability in GSS can also affect decision processes and outcomes. This paper reviews theories about voting methods and their implications to GSS. A classification of voting methods based on information exchange is proposed to examine the effect of voting methods on groups’ decision processes