State school finance systems can play an essential role in directing additional resources to schools serving economically disadvantaged students, and research suggests that these resources can make a measurable difference in student outcomes. The vast majority of states (45) allocate some funding to districts based on their enrollment of economically disadvantaged students, though approaches differ. An earlier brief in this series, "Splitting the Bill: How Can School Finance Systems Support Students With Additional Learning Needs?," covered some principles and best practices for funding for economically disadvantaged students, along with other groups of students with additional learning needs. This brief goes even deeper into the topic.