This study investigates how advertising-based sustainability messaging is influenced by message-source congruity, narrative engagement, and identification. Using two experimental designs, the results show that sustainability messaging improves evaluations of sources that are congruent with sustainability messaging, when compared to sources that are not. Featuring groups of people – rather than an individual – in these messages may work to further magnify those positive evaluations (Study 1). Most interestingly, while narrative messaging was not on-the-whole more persuasive, a message presented in narrative form appears effective in overcoming message-source incongruity in the context of sustainability-focused advertisements. [ABSTRACT FROM AUTHOR]