The investigation was conducted to document the prevalence of site-based management (SBM) as a form of decentralized governance in public schools. United States Government school census documents were used for the population from which 770 school districts were drawn for the sample. Superintendents from 187 school districts responded to Phase I of this investigation. Superintendents were asked if their school district used SBM, composition of site councils, selection processes of council membership, authority granted, content of decisions, and impact on student achievement;Phase II compared different models of SBM and their impact on student achievement. Three school districts were selected with different models of SBM: superintendent-initiated SBM, school board-initiated SBM, and state-mandated SBM. Comparisons were made between the school districts in the following areas: granted authority, content of decisions, time spent on issues, elements of functioning councils, and impact on student achievement. Comparisons were also made between parents and other members of the councils regarding the perceived impact of the different SBM models on student achievement;Statistical procedures used for this investigation were ANOVA, Scheffe, Bonferroni, and chi-tests;Fifty-four percent of the superintendents responding to this survey indicated their school district did use SBM. The superintendent-initiated SBM was the most frequent form of SBM. Authority granted to SBM councils was most frequently curriculum, followed by budget and personnel. The findings from the more detailed examination of SBM councils showed that state-mandated SBM councils spent more tune on curriculum and had a larger impact on student achievement than councils from superintendent-initiated or school board-initiated SBM;Seventy-seven percent of the superintendents of SBM governance reported SBM to have "some" to "moderate" impact on student achievement. Parents on councils from state-mandated SBM rated their councils to have a higher impact on student achievement than other forms of SBM. Parents on councils rated their councils to have a higher impact on student achievement than did other members of the councils.