A public system cannot be accountable for ownership it does not measure. What data systems trace determines what decision-makers can see, compare, authorize, protect, and correct.This is the ninth paper in IIBD's Community Wealth Infrastructure series. It turns to measurement: what a public system must count in order to be accountable for ownership at all, and introduces the Community Wealth Balance Sheet.Part of the Community Wealth Infrastructure Series (Working Paper No. 9), published by IIBD.Suggested citation: Williams, R., & Dillon, D. (2026). Measuring what communities own: The Community Wealth Balance Sheet and data accountability for public decisions (Community Wealth Infrastructure Series, Working Paper No. 9). IIBD.