In any social movement, the message and messenger matter. This presents challenges and opportunities for movements like Black Lives Matter (BLM), as the same message can reach different groups to varying effects depending on who delivers it. We study these dynamics directly using an experimental design that gives some respondents a choice about whether to hear a Black man’s opinions about BLM. Our design reveals what a standard experiment might miss: messages from Black messengers reach broad audiences and produce more support for BLM. However, among those unwilling to hear a message from a Black messenger, encountering a pro-BLM message from a Black messenger causes backlash which obscures the broader, positive effects of the message on its likely audience. These skeptics, however, are less hostile to and potentially persuaded by the same message from a white messenger. The results demonstrate how targeted messaging can increase support for social movements.