This paper presents findings of a study that described the existing nature of school-based management (SBM) structures and procedures associated with school-development planning in Western Australia. It also examined the impact of SBM on the curriculum and professional activities of teachers. Data were obtained through analysis of official policy guidelines and school documents and a survey of 279 teaching staff from 12 secondary schools in Perth, Western Australia. Findings show that the administrative structures and processes in the schools were generally consistent with government policy guidelines. However, the structures and procedures had little effect on classroom practices at the school level. Twenty-nine percent of survey respondents felt that participation in school-development planning informed and improved teaching and learning in the school. For almost 71 percent of the teachers, the documented plans bore little resemblance to actual classroom practices. In short, teachers did not perceive that SBM contributed positively to their schools' educational programs. Rather than coordinating the work of the school with the stated priorities of the education system, SBM appeared to have had the opposite effect. Unintended consequences included reduced time for curriculum planning and interdepartmental fragmentation. One table and one figure are included. (Contains 16 references.) (LMI)