This research studied the effects of a Group Decision Support System (GDSS) for face-to-face negotiations in three-person groups. The GDSS equipped the groups with full information about each other’s individual preferences regarding a resource allocation problem. In a partial replication of a GDSS experiment, we examined the effect of this full information treatment on post-meeting consensus level, the level of integrative behaviour, and the level of distributive behaviour in the groups. 96 threeperson groups participated. Groups using the GDSS reached a higher level of post-meeting consensus compared to groups not using a GDSS. This finding supports the theory that negotiators lower their demands and increase their involvement if full information is available. No support could be found for the hypothesis that the treatment had an impact on integrative or distributive behaviour.