ABSTRACT Drawing from the literature on the psychological harm of hate speech and the source magnification framework, we investigated the effects of hate messages from multiple sources on target group members in the context of Twitter. An online experiment conducted with Black Americans living in the United States provided evidence for source magnification of anti-Black messages. In the experiment, participants were exposed to one of three sets of tweets: hate tweets from multiple sources, hate tweets (of identical content) from a single source, and non-hate (control) tweets. The results showed that hate tweets from multiple sources, when compared to the identical hate messages from a single source and to the non-hate tweets, led to greater emotional distress, which, in turn, resulted in greater likelihood of attributing ambiguous social situations to racial prejudice. The findings provide initial evidence for source magnification of hate messages in the context of communication based on social media where simultaneous exposure to asynchronously posted hate messages from multiple sources is likely to happen. The findings also suggest that multiple-source hate messages, when compared to single-source hate messages, are more likely to indirectly result in potential relational harm.