This research note presents preliminary research into the relationship between the racial composition of public schools in school districts and the percentages of white students in nonpublic schools in those districts. Specifically we ask two questions: Is the enrollment of whites in non-public schools associated with minority predominance in public schools? Is there an association between the enrollment of whites outside of the public school system and the academic performance of students in the public school system? Using two- and three-level hierarchical linear models, we find that school districts that have more whites in nonpublic schools tend to contain public schools with larger percentages of minority students. Further, at both the school and individual levels, achievement test scores tend to be lower in districts in which white students tend to be enrolled outside of the public school system. In addition, the achievement gap between white and minority students tends to be greater in districts with relatively more students in nonpublic schools. These findings are consistent with the argument that the withdrawal of white students from the public school system is negatively related to academic achievement because it tends to concentrate minority students in public schools.