Federal regulations require that all students in specified elementary, middle, and high school grade ranges participate in state assessments used for accountability. The Individuals with Disabilities Education Act (IDEA) requires that all children with disabilities are included in all general state and districtwide assessment programs with appropriate accommodations and alternate assessments, regardless of whether the assessments are used for accountability. For students with the most significant cognitive disabilities, ESSA places a one percent threshold on their participation in a state's alternate assessment based on alternate academic achievement standards (AA-AAAS). The purpose of this report is to provide an overview of federal statutory language on student participation in state summative assessments used for accountability as well as the participation requirements for states requesting waivers from the 1% threshold on participation in the AA-AAAS. It also includes a review of the reasons why states have found it challenging to meet the 95 percent participation rate, and the extent to which states have met federal testing participation requirements. The report includes examples of strategies several states used to address assessment participation. Addressing stakeholder questions and clarifying the value of testing can encourage student participation in state assessments. Communication tools and the development of a communication plan can support states in communicating testing purpose and importance clearly, and addressing stakeholder questions and concerns about testing.