Mimicry enhances one's judgments of the mimicker when it is directed toward the self. However, often interactions do not involve only the participants; observers also judge people, and such judgments are influenced by social identities. So, does mimicry also have positive effects even on observers' evaluations of the mimicker? Furthermore, does that hold even if the mimicker is an out-group member? To answer these questions, we used two video experiments (N₁ = 377; N₂ = 670) to compare mimicry and neutral (no mimicry) interactions between two individuals who were primed to be in either the participant's in-group or out-group. In both studies, we found the expected negative out-group bias when participants observed the neutral interaction but only for competence-related variables. However, such biases were diminished in the mimicry condition, indicating that mimicry, even when it is merely observed and directed at someone else, may alter mimicker-related attitudes stemming from social identities. Our findings therefore contribute to the literature on reducing intergroup prejudice by demonstrating the behavior-based malleability of a negative out-group bias. (PsycInfo Database Record (c) 2023 APA, all rights reserved).