Knowledge of leadership is an important consideration for both teacher preparation and performance, and effectiveness in both areas can be improved through an understanding of the relationship between the dynamics of the classroom social system and the leadership style (motivation) of the teacher, and the conditions under which they meet. Leadership style, as determined by a Least Preferred Co-Worker (LPC) Scale Test, can be divided into two types: relationship motivated and task motivated. The first type is interested in good relationships with people and encourages group members to participate and to offer different ideas. The second type finds the task very important and a poor co-worker as an obstacle who may prevent task accomplishment. Components of the leadership situation involve leader-member relations, task structure, and position power. If leadership styles do not match the situation, it is best to modify one of the three components of the situation, i.e., modify level of rapport with students, select different procedures or structures, or modify authoritarian (or shared decision making) mode. Learning how to adjust will improve teacher leadership and effectiveness. (DS)