This study focuses on employees' work-related social media use. The multivalent involvement of social media in corporate processes calls for attention to how employees' social media use is conceptualized and managed. Drawing on a sample of 1179 knowledge workers, the study explores how employees perceive their communicative roles, how contextual factors shape these perceptions, and how communicative role perceptions, in turn, are associated with work-related social media use. The findings demonstrate that leadership support and employees' perceptions of the anticipated impact of their communication are positively related to role perceptions, and the more employees define their communicative roles as an expected part of their work, the more likely they are to use social media for work-related purposes. This study is highly relevant to scholars and managers as it draws attention to expanding workplace roles that emerge in relation to advancements in, and the adoption of, new information and communication technology.