In this article, the author attempts to show the role played by effective teams in creating and expanding effectiveness of military organization. The author presents not only the changes that should be implemented in an organization in order to establish conditions conducive to the creation of organizational effectiveness, but also influence of various factors on building an effective team. The critical elements in the ability to build an effective team are organizational context, leaderships, group processes, and team culture. In a time of military personnel downsizing the necessity of building the effective teams is important in the concept of organizational effectiveness. Additionally, a military organization is largely conservative in its hierarchy and shows little inclination to change in general. However, building effective teams as an element of effectiveness, in view of the character of this organization, is neither an easy nor a short-lasting process.