Educational policies mandate the consideration of accommodations so that students with disabilities become proficient in the objectives outlined by state academic content standards and demonstrate proficiency on high-stakes assessments. However, neither policies nor empirical research provide sufficient guidance for educators to effectively select and implement accommodations. This study reviews the effectiveness of accommodations for students in the special education eligibility category of emotional disturbance and those with diagnoses of attention deficit hyperactivity disorder (ADHD). First, we propose definitions that delineate accommodations from modifications and interventions. Next, we identify strategies that could serve as potential accommodations for this population. Next, we conduct a systematic literature review and calculate effect sizes to evaluate the effectiveness of the included strategies. Finally, we review the evidence to determine whether each included strategy meets the proposed definition of an accommodation. Although several potential strategies are beneficial to youth with ADHD and/or emotional and behavioral disorders, this review indicates that very few purported accommodations actually meet all the criteria in the definition of accommodations, and there is very little evidence supporting the effectiveness of commonly recommended accommodations for youth with behavioral challenges. Our critique of the state of the science on accommodations highlights several important issues that can be used to inform current research and practice in schools.