In theory, the charter school concept is based on a trade-off or exchange: greater autonomy for increased accountability. Although charter schools have been operating for more than 10 years, little is known about charter school autonomy in practice. This mixed-methods study used survey and case study data to examine the degree of autonomy of charter schools across the country and the factors limiting school autonomy. The findings indicate that many charter schools do not have high levels of autonomy, with schools least likely to have control over budgetary decisions. In addition, school autonomy is influenced by state laws, relationships with authorizers, and partnerships with educational management organizations and community-based organizations. Finally, the levels of autonomy in some schools were dynamic, with schools experiencing less autonomy over time. (Contains 5 tables and 12 notes.)