As more students with disabilities are included in general education classrooms, many obstacles must be overcome before parents, teachers, students, and administrators deem inclusion effective. This article identifies seven "sins", which are barriers to inclusive practices in secondary schools: Negative teacher perspectives; lack of knowledge regarding special education terminology, issues and laws; poor collaboration skills; lack of administration support; limited instructional repertoire; inappropriate assessment procedures; and conflict between scheduling and time management. The literature on inclusive practice is cited as evidence for each "sin," and advice for avoiding each of them is provided.