A fundamental ideal of our democratic republic is that every person has some way through which she/he can participate in decisions which directly affect her/him. To some extent, most teachers are able to recognize this ideal in their private lives. It seems logical that this realization would also carry over and prevail in an individual's working life. This would also include the teaching profession and school administration. With few exceptions, teachers seemed to favor participation in decision-making (Yarborough, 1976). The extent of teacher involvement in decision-making and representation together were strongly related to the effectiveness of the units (Berlinger, 1975). Nowadays, the school effectiveness research has become one of the most dynamic areas of study in education. Schools are complex social systems in which different elements or characteristics combine in different ways and different combinations in various schools (Miller, 1994). The government will increase the number of comprehensive high schools in Taiwan, when the number of comprehensive high school increases, it is essential to understand whether there is a relationship between teachers' participative decision-making and school effectiveness. (Contains 10 tables.)