Charter schools are publicly funded schools that have considerable independence from public school districts in their curriculum development and staffing decisions, and their enrollments have increased substantially over the past two decades. Charter schools are changing public and private school enrollment patterns across the United States. This study analyzes district-level enrollment patterns for all states with charter schools, isolating how charter schools affect traditional public and private school enrollments after controlling for changes for the socioeconomic, demographic, and economic conditions in each district. While most students are drawn from traditional public schools, charter schools are pulling large numbers of students from the private education market and present a potentially devastating impact on the private education market, as well as a serious increase in the financial burden on taxpayers. Private school enrollments are much more sensitive to charters in urban districts than in non-urban districts. Overall, about 8 percent of charter elementary students and 11 percent of middle and high school students are drawn from private schools. In highly urban districts, private schools contribute 32, 23, and 15 percent of charter elementary, middle, and high school enrollments, respectively. Catholic schools seem particularly vulnerable, especially for elementary students in large metropolitan areas. The flow of private-school students into charters has important fiscal implications for districts and states. When charters draw students from private schools, demands for tax revenue increase. If governments increase educational spending, tax revenues must be increased or spending in other areas reduced, or else districts may face pressures to reduce educational services. The shift of students from private to public schools represents a significant shift in the financial burdens for education from the private to the public sector. Appended are: (1) Descriptive Characteristics of States and Large Cities; (2) Variable Means and Regression Results for Elementary School Students; (3) Variable Means and Regression Results for Middle School Students; (4) Variable Means and Regression Results for High School Students; and (5) Enrollments and Numbers of Schools by School Type and Urbanicity, 2008. (Contains 36 tables and 67 notes.)