There is some scepticism about the effectiveness of equity funding policies (EFPs). However, many studies focus only on one particular EFP in one education system. The present paper draws lessons from a review of the North American and European literature. In general, EFPs did not always meet the expectations of policymakers and educational agents. Five potential causes emerge from our review: (1) Matthew effects in the baseline resourcing of schools; (2) the ineffective use of additional resources; (3) ineffective targeting; (4) flaws in monitoring and evaluation; and (5) the general social and educational context in which EFPs are implemented.