This paper contrasts three theoretical positions which lead to different predictions about the impact on instruction and learning of enhanced teacher roles in school and classroom decision making. The "teacher professionalism" view maintains that empowerment enhances instruction and learning, the "bureaucratic centralization" approach argues that empowerment impedes effective teaching and learning, and the "loose coupling" perspective suggests that empowerment is largely irrelevant for what happens in classrooms. The assumptions that underlie these perspectives and the conditions under which one or another may be more plausible are discussed. A review of research finds little evidence to support or disprove the claims of any of the three views. Seventh and eighth grade teachers' perceptions of empowerment are then related to the achievement of their students in math and science. Results, which were inconsistent across grade levels and subjects taught, indicated that teacher control over curricular content may be detrimental to achievement, but control over teaching methods may be beneficial. Participation in administrative decision making also yielded inconsistent results, while teacher influence over school policies yielded no effects. The study concludes that the effects of empowerment depend on which aspect of teaching is empowered and the domain in which empowerment occurs. An appendix presents data supporting study findings. (Contains 34 references.) (JDD)