A decision has been taken by the selection of alternatives from a variety of options available at a given moment, it is an essential part of our daily life. We will appoint decision „a solution adopted by a system (person, group, organization, mass caterer) with a view of solving a problem”. This situation leads to the approach of making-decision process from completely different perspective from that of individual decision. As it's all about group in human quality to the subject TDM, specific problems arise dynamics of the group. Collective situation becomes a potential source of activation, the mobilization of energy social phenomena. Degree of involvement of participants is different, that is reflected into the dynamic of the group. An attempt was made to identify factors affecting collective decisions. Depending on the nature of the subject problem to discussion group, the rules in relation to which it is adopted decision are different. Groups are heterogeneous by definition: the participants are driven by special interests, each of them with diverse information and different opinions and joins at different values. All these differences are translated by discrepancies, opposition between „agreement” and „disagreement” within the framework of the group. External conflict between a person and other internally transposed by a tension is required to be reduced by solving disagreement. The members of the group have different knowledge, so that the group's knowledge is greater than knowledge held by any of its members. In this case each member of the group has some of the information that the others do not hold. As a result, the knowledge, information, opinions available to each group will determine its initial orientation. In group discussion, it is much more likely that the participants to come up with arguments in favor of its initial attitude, causing segregation among all members of the group. It is shown that the members of the group of decision tend to be far less moderate in assuming decision with increased level of risk, because they believe that the potential negative consequences of their decisions will be responsible for all members of the group.