Professional references are widely used in hiring decisions, yet their effectiveness remains largely understudied. We analyze structured ratings collected from the professional references of teacher applicants and conduct an experiment to see whether the ratings influence hiring managers' assessments of applicants and hiring decisions. We find little evidence that providing reference ratings to hiring managers influences their evaluations of candidates or hiring choices in productive ways. Importantly, we also find that reference ratings are predictive of future job performance. The result is a paradox: reference ratings offer potentially low-cost, high-value information, but hiring managers do not appear to make productive use of them.