This international, mixed-methods study revealed parents' perceptions (N = 82) of the effectiveness of classroom accommodations for students diagnosed with Pediatric Acute-onset Neuropsychiatric Syndrome (PANS). PANS can transform a child's function suddenly and dramatically. These students demonstrate abrupt deficits in previously intact school performance, rendering formerly proficient children incapable of regulating their own behavior, engaging in social activities, or demonstrating school skills they competently achieved previously. As debilitating as PANS may be, there is scant research as to its impact in the classroom despite the average age of onset to be in school-age children. This study triangulated descriptive, quantitative-survey data with phenomenological perspectives data to examine parent perceptions of the effectiveness of accommodations when PANS is suspected. Results proffered recommendations for best practice and identified four themes. First, parents reported that student behavior issues and academic losses persist and may not return to baseline, most notably in academics. This finding underscores the importance of prompt, data-informed, meaningful collaboration among parents, school personnel, and the medical community to prevent life-long learning challenges. Second, parents reported that although school is important and should provide for all students, the level of debilitation incurred during a PANS exacerbation may not be reasonably managed in the education setting despite school-based accommodations. Third, parents perceived medical treatment to increase the effectiveness of school-based accommodations. Fourth, this study's findings corroborated themes identified in prior studies (fear, frustration, concerns not being acknowledged, and the impact of the condition on home, school, and family quality of life). [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]