Social media have dramatically altered the communication landscape, offering novel contexts for individual expression. But how do youth who are civically engaged off-line manage opportunities for civic expression on social media? Interviews with 70 U.S.-based civic youth aged 15 to 25 revealed three main patterns characterizing the relationship between off-line participation and online expression: blended, bounded, and differentiated. Five sets of empirically derived considerations influencing expression patterns emerged: organizational policies, personal image and privacy, perceived alignment with civic goals, attitudes toward the platform(s), and perceptions of their audience(s). Most civic youth express the civic online, yet a minority highlight tensions that lead them to refrain from sharing in certain or all online contexts.