Education finance shapes what is possible in every school in the country. And finance equity is a critical step toward enabling other forms of educational equity for students who are underserved in under-resourced schools. But in too many states, the system of funding for schools remains inequitable, inadequate, and opaque to all but a few. Even in states that adhere to high-level best practices in school finance equity, funding systems can be rife with technical pitfalls or loopholes that jeopardize equity. These systems are unlikely to give schools what they need to provide an excellent education for all students. Advocates at the state and local level have a powerful role to play. While school funding systems are politically and technically difficult to change, over the past few years, advocates across the country have successfully fought for change via legislation and lawsuits. To do so effectively, advocates need a solid understanding of how school finance works in their state and how it could work better.