I use data from the Olympic sport of dressage to explore in‐group biases among judges. Dressage – the only international sport with subjective performance evaluations in which men and women compete as equals – provides a rare opportunity to identify multiple in‐group biases in the same naturally occurring setting. While, on average, judges are not biased in favour of either gender, they exhibit substantial biases in favour of (i) athletes of their own nationality, and (ii) athletes of the same nationality as the other judges in the competition. Heterogeneity across competitions suggests that biases increase as group identity becomes more salient.