The paper includes introductory information regarding the group in the military organization as well as some conceptual assignation regarding the working groups and teams, their types and finally the designation of the group, its training and its reconstruction. The most ancient and largely spread classification of the work group stipulates their differentiation according to the degree of formality and the type of relations among its members. According to such a classification we have on the one hand the formal groups, and the informal groups on the other. The former ones are organized after norms, laws and regulation established in an official manner. Another distinction will be made on the principle considered by some others essential for the increase of work performance. Levine and Moreland thought that the degree of ability belonging to the team members (ability is defined as the mixture between autonomy and power) represents such a fundamental criterion which may explain the higher or lower performance in each situation. A simple specification of the types of groups and working teams has revealed a series of characteristics. Still, a more developed psychosocial analysis would be imposed as a necessity. Although we do not give up to the distinction made between group work and team work, the term group work will be preferred in the following pages because of its greater use among the specialist of the psychological and psycho organizational literature.