This report provides 10 lessons about how to ensure inclusive assessment practices for students with disabilities and English learners. In addition to the 10 lessons, it provides foundational information on the characteristics of these students that require consideration during all phases of assessment design, development, and implementation. The focus of the "Guidebook" is large-scale summative assessments rather than interim and formative assessments; it does not address accountability considerations. The purpose of the "Guidebook" is to remind all assessment, special education, and other personnel in state departments of education of the lessons that have been learned, and to share those lessons with new personnel in state assessment, special education, Title I, and Title III offices.