This study investigated a range of impacts that a computerized group decision support system (GDSS) might have on group decision-making processes. A general model posited 13 possible GDSS impacts. The research strategy was to identify which of these impacts were likely to result for the specific GDSS and for the budget allocation task employed in this study and to focus on these in data collection and analysis. The design contrasted (a) groups using a computerized GDSS with (b) groups using a manual, paper-and-pencil version of the GDSS and with (c) baseline groups given no support system. GDSS impacts were measured by interaction analysis of group decision-making processes. Results partially supported our predictions and suggested some changes in the model. Results suggested that the GDSS improved the organization of the decision-making process but that it may have led to less thorough and critical discussion.