In many scientific contexts, peer review can be either single-blind or double-blind: in single-blind review, research work (e.g., manuscripts, proposals) is reviewed alongside information on the author(s), whereas in double-blind review, information on the author(s) is withheld. We will report results from a randomized experiment conducted in collaboration with a grantmaking body, in the context of the grantmaker reviewing proposals in one field of science. By comparing scores across single-blind and double-blind reviews for groups of different characteristics, we can test for potential biases in the review process.