This Dissertation had three main purposes. They were (1) to identify leadership profiles of high school principals, (2) to test the theory of oelongingness in relation to student achievement, and (3) to determine how far the leadership variables   influenced student achievement. A leader, in any circumstance, plays a key position in the organization he is engaged in. It is in the leader's hands that an organization could change forwards or backwards. On the one hand, progress and backwardness in school organization are primarily dependent upon   the   status of teachers* maturity. On the other hand, all   aspects     of school progress and backwardness are determined   by   the leadership of the principal. It was found in this study that high school teachers in West Sumatra already possessed a relatively high degree maturity in their tasks.   However, school principals   in managing their teachers' maturity utilized a combination of two basic styles, i.e., the "selling-telling"   style and the coercive power relying on the official position as a means of reinforcing the teachers' obedience.   The behavioral combination — the authoritative style   and power that compells the leader's own intention, — could create tranquility on the surface but could not   solve the real problems and developed new ones.   The elements of teachers' "creativity" seemed to be taken   over   by the dominant school principals.     Teachers'    teaching "aptness" tended to fade away and the teachers held   out with the remaining energy and fatigue caused by too many interminable instructions. Through statistical testing, the theory of belongingness, which is almost vanished   from   the   scientific arena, was confirmed.   As a matter of fact,     high school teachers and principals in West Sumatra   were found   to possess a high degree of belongingness feeling   in   their effort at running the school organization. It was found, to a certain extent, that the higher the quality of   belongingness perception among teachers and principals, the higher'the quality of achievement (absorptive capacity) of their students. Therefore, there was   no   reason to deny that the concept of belongingness    had   acquired scientific legality and a proper place equivalent to that of other leadership theories.