The expectation in this country is that all students should be able to succeed in school. Yet new data and accountability agendas have heightened attention to performance disparities between students with different identifiable needs--needs that stem from poverty, disability, or limited English proficiency. Educators and policymakers know that such students often arrive at school with myriad challenges that call for increased resources to help them reach their full potential. To address gaps in student performance, many policymakers look to adjust the state's funding formula. Some layer on funds for specific programs or services, while others push for a wholesale overhaul of the way resources are allocated (e.g., advocating for a student based allocation system). But many policymakers find themselves trying to do this work in the dark. This brief offers guidance to help state policymakers ask the right questions and tap their own data when designing funding policies to serve high-needs students.