Most studies have focused on whether charter schools perform better than TPS. However, for the vast majority of students who remain in TPS, a more relevant question is whether charter schools have a positive or negative impact on their schools. This study uses national, district-level panel data to examine how charter school prevalence influences the academic performance of students from the same-district TPS. Our primary data source is the Stanford Education Data Archive (SEDA). The SEDA provides the average English and mathematics test scores for all US districts between 2009 and 2015. We assess the role of charter school penetration on TPS students' performance in recent years, using various measures of charter school prevalence. Employing the district fixed effects model exploiting within-district variation, we find a small but negative association between charter school prevalence and both math and English achievement. Based on our findings, it seems premature to emphasize the virtue of competition charter schools bring to public education, and allocating more resources into charter schools should be undertaken with great caution.