The purpose of this study was to determine Pennsylvania public high school instrumental music teachers' perceptions of changes to instrumental music instruction that may have been the result of a narrowing focus on student performance on standardized tests and sanctions linked to the No Child Left Behind Act of 2001 (2002). The study used a descriptive design to investigate ways that standardized testing may have influenced student opportunities to participate in school instrumental music, instructional time available for instrumental lessons and performing ensembles, budgetary resources and funding sources, staffing, and instrumental music curricula in Pennsylvania high schools. Data were gathered via an anonymous web-based survey. Of the entire population of 710 full-time high school instrumental music teachers in Pennsylvania, 304 responded. Of those, 247 successfully completed the survey and were appropriate for analysis. Results suggested that across PA high schools, instrumental music opportunities were varied and inconsistent with regard to instructional time, financial resources, access and availability of students, and support for instrumental music within the larger curriculum of the schools. These inconsistencies may have resulted in unequal opportunities to participate in instrumental music programs, partially because of funding and policy priorities at the state and local level that value test-based accountability rather than more comprehensive methods of evaluating child development and learning. Prior research suggested that opportunities to participate in instrumental music were linked to individual and group standardized test performance. Schools in very large urban districts with high percentages of low-income and minority students were the most likely to face reductions in instrumental music opportunities. Implications included the possibility of inequitable reductions to music programs potentially undermining efforts to help reduce or prevent achievement gaps. Reductions in instrumental music opportunities for elementary level students was a particular concern since neurobiological research findings suggest special benefits for early childhood music instruction. Recommendations for further research included replication of the study using identifiable data, case studies of individual high schools, the continuation and expansion of longitudinal studies between neuroscientists and music educators, and a survey of school administrator attitudes toward music education.