Just as one has a different sense of a mountain from each approach to it, so each group theory gives differing and somewhat overlapping aspects of group functioning. Each approach can help explain part of what is going on. Jung focuses on the perceptual and evaluative aspects of the individual and the resulting group consequences. Schutz focuses on the interpersonal needs of inclusion, control, and affection. The three sets of needs are always present but to a varying degree in different individuals and in different phases of group development. Groups start with inclusion behavior, which is followed by the emergence of control and finally affection behaviors. Important for a group's existence is members' compatibility, the satisfaction of one's own and each other's needs. Bion considers group emotionality. The main emotional assumptions which are reflected in group behavior are dependency relations between the members and the leader, fight-flight or aggression-withdrawal, and pairing or shared interest in which members may be engaged. As the group seeks to accomplish its work it has to come to terms with its emotionality as expressed through the shifting basic (emotional) assumptions. (Author/JEL)