ABSTRACT Research has shown that listener bias and stereotyping affect listeners’ attitudes towards L2 English speakers [Lindemann, S., Litzenberg, J., & Subtirelu, N. (2014). Problematizing the Dependence on L1 Norms in Pronunciation Teaching: Attitudes Toward Second-Language Accents. In J. Levis & A. Moyer (Eds.). Social Dynamics in Second Language Accent (171–194)]. However, little research has explored ways to mitigate such prejudice to combat the linguistic discrimination prevalent in our society [Kang, O., D. Rubin, and S. Lindemann. 2015. “Mitigating U.S. Undergraduates’ Attitudes Toward International Teaching Assistants.” TESOL Quarterly 49 (4): 681–706; Subtirelu, N. C., and S. Lindemann. 2016. “Teaching First Language Speakers to Communicate Across Linguistic Difference: Addressing Attitudes, Comprehension, and Strategies.” Applied Linguistics 37 (6): 765–783]. The present study explored the effect of a one-week intervention on U.S. undergraduate students’ perception of L2 speakers. This study included three intact undergraduate-level writing classes (n = 25 each), two intervention groups and one control. Before the intervention, all students completed a perception questionnaire to measure listener perceptual judgement of language attitude, comprehensibility, and accentedness of L2 English speakers. The intervention included (a) one 50-minute discussion which explicitly addressed social justice issues related to multilingual speakers, designed according to the cognitive dissonance theory [Festinger, L. 1957. A Theory of Cognitive Dissonance. Evanston, IL: Row, Peterson] and (b) three 50-minute laboratory sessions for reflection papers. An immediate post-test and a delayed post-test (11 weeks after) were administered. Linear mixed-effects models showed significant and sustained improvement of language attitude and comprehensibility ratings for the intervention groups across time, but not for the control group. The findings provide a relatively short, easily replicable, and sustainably effective intervention program to mitigate listener bias against L2 English speakers.