This quasi-experimental paper by Michael Gilraine, Uros Petronijevic, and John D. Singleton explores whether attending different types of charter schools have differing effects on nearby students’ test scores. The study classifies charter schools into two types, schools that use traditional lecture-style instruction and focus on core curriculum (non-horizontally differentiated) and schools that focus on project-based and experiential learning (horizontally differentiated). The authors compare students who live within 2.5 miles of a charter school of either type with students who live between 2.5 and 5.0 miles of a charter school of either type. They find that students who live near a recently opened non-horizontally differentiated charter school have higher math scores than students who live further away. The authors do not find an effect on the math scores of students who live near a horizontally differentiated charter.