The Schools for the 21st Century (C21) Consortium was created in 1988 to produce change within 30 schools in a zone of the Seattle School District. Changes in four areas--staff development, networking among the schools, school-community linkages, and school restructuring--were implemented under "School Focused Leadership," a move toward school-based management. This paper presents findings of a study that sought to: (1) categorize the kinds of decisions that school sites make; and (2) determine the effect of shared decision making on student achievement outcomes, both in terms of overall gain and ethnic gap reduction. To determine the extent to which "School Focused Leadership" was really occurring in the schools, a group of teachers on the C21 advisory council developed a questionnaire and administered it to teachers in 19 C21 elementary schools in 1992. A revised version was administered to teachers in 13 of the C21 schools in 1993. The data show a curvilinear relationship between shared decision making and student achievement. As the C21 schools moved at different rates toward participative decision making, they showed a drop in the ethnic gap reduction (EGR). As they reached a point of greater influence in decision making, EGR scores rose. The data are consistent with other research findings that have found that reduction in student outputs occur as change is initiated and that outputs increase as change is institutionalized. Three figures and one table are included. (LMI)