Research has shown that people in decision situations tend to change the psychological attractiveness of the decision alternatives in favour of their own preferred alternative after the decision has been made. The function of this consolidation is to create a decision that can withstand future threats against its optimality (Svenson, 1992; 1996). Consolidation processes have primarily been studied in individual decision situations. Less attention has been paid to such processes in group decision making. The aim of the current research was to study how different forms of decision making in large groups affected consolidation among individual group members. In two experiments, high-school students read a vignette about a hypothetical decision situation in their school. In one condition, participants were informed that the final decision was made by out-group authorities (the principal and the teachers), and in the other that in-group authorities (student representatives) made the decision. Participants indicated their own preferred decision alternative, and rated the attractiveness of the different alternatives before and after they received information about the final decision. Results showed that the decision procedure was perceived as more fair when made by in-group, as compared to out-group authorities. However, with in-group authorities, participants also showed a stronger tendency to consolidate their own preferred alternative. This tendency was particularly strong when the in-group authority had chosen another alternative than the one participants preferred. Consolidation may increase in in-group contexts because decisions by in-group members can provide people with important self-validation, and therefore the decision becomes more personally involving.