We report the first investigation of whether observers draw information about mindsets from behavior, specifically prejudice confrontation. We tested two questions across 10 studies (N = 3,168). First, would people who observe someone confront a biased comment (vs. remain silent) see them as endorsing more growth (vs. fixed) mindsets about prejudice and bias? If so, would the growth mindset perceptions that arise from confrontation (vs. remaining silent) attenuate the backlash that observers exhibit against confronters? We investigated these questions using scenarios (Studies 1, 2a–b, 4, 5a–d), naturalistic confrontations of national, race, and gender stereotypes reported retrospectively (Study 3), and an in-person laboratory experiment of actual confrontations of racial bias (Study 6). Correlational and experimental methods yielded support for our core hypotheses: People spontaneously imbue someone who confronts a biased comment with more growth mindset beliefs about prejudice and bias (Studies 1, 2a–b, 4, 6), regardless of whether participants observe the confrontation (Studies 1, 2a–b, 5a–d) or are being confronted themselves (Studies 2a–4, 6). The growth mindset perceptions arising from these confrontations suppress backlash, assessed by classic interpersonal perceptions (Studies 4–5) and judgments of interpersonal warmth and willingness to interact again in the future (Study 6), both when the confronter was a target of the biased behavior (Studies 1–5), and when they were an ally (Study 6), in both correlational studies (Study 3–4) and when growth mindset (about personality, Study 5; about prejudice, Study 6) was manipulated, confirming causality. We discuss implications for the study of mindsets, confrontation, and intergroup relations