Public responses to nonprofit social media messages: The roles of message features and cause involvement

•Test what makes nonprofit social media posts effective in driving behavioral intent.•Information sharing is predicted by a message appeal × interactivity interaction.•Information seeking is predicted by a message appeal × cause involvement interaction.•Information seeking is also predicted by an interactivity × cause involvement interaction.•Donation intention is predicted by an interactivity × cause involvement interaction. This study aims to answer the question of what makes a nonprofit social media message effective in driving favorable behavioral outcomes from publics. Toward this purpose, it draws on multidisciplinary theoretical insights from public relations literature, functional interactivity research, the Elaboration Likelihood Model, and the limited capacity model of motivated mediated message processing. It theorizes an information-processing account to predict and explain the interplay among social media message appeal (emotional versus informational appeal), functional interactivity (high versus low interactivity), and individuals’ cause involvement (high versus low involvement) on public behavioral outcomes including information sharing, information seeking, and donation intentions. Results of an online experiment revealed significant two-way interactions between message appeal and functional interactivity, between message appeal and cause involvement, and between functional interactivity and cause involvement on different behavioral outcomes. These results bring novel theoretical and practical insights on when, how, and why nonprofit social media communication can be effective.