AbstractGender biases have been documented in many areas including hiring, promotion, or performance evaluations. Many of these decisions are made by committees. We experimentally investigate whether committee deliberation contributes to gender biases. In our experiments, participants perform a real effort task and then rate the task performance of other participants. Across treatments we vary the extent of deliberation possible. We find that deliberation increases gender biases. We explore several mechanisms and test two interventions. Randomizing the order of speaking does not reduce gender bias, but an information intervention where raters are informed of gender bias in prior sessions does.