Our study investigates the extent to which social media users engaged with organizations online exhibit traditional characteristics of boundary spanners, and whether this engagement results in more positive public relations outcomes for organizations. An online survey was conducted among 403 students and structural equation modeling was used to test a proposed theoretical model. Starbucks and Amazon were selected for this study as both are organizations with a substantial online presence in social media. Results show that social identity and self-efficacy had a positive impact on boundary spanning behaviors, but boundary spanning behaviors did not have a significant impact on social media engagement. However, this study makes an important contribution to current theory in public relations as the results also provide strong empirical evidence for the positive effects that social media engagement has on both relational satisfaction and relational commitment.