Abstract Social media is one of the most contextually based media ever created. As such, the effects anticipated by priming theory would be expected to be especially strong. Using an online experiment, this study assessed the effects of linguistic tone and message relatedness present in the context of social media on publics’ attitudes towards organizations. It was expected that positive and negative tone would have positive and negative effects, respectively, and that the relatedness of the contextual prime would enhance those effects. About 100 participants in the study were randomly assigned to an experimental group to see a prime in the format of the popular social media site, Twitter. An analysis of the results showed that only negative primes had a significant effect on publics’ attitudes towards organizations, possibly reflecting an expectancy violation effect. Public relations professionals are called to engage in broader environmental monitoring to ensure their messages will be most effective.