Social media activism has become very relevant for many student activist groups. How can political use of social media be motivated? The concept of Social Media Political Efficacy was proposed to resolve inconsistencies in prior theories of social media activism. A survey (n = 222) of members of 3 student activist groups showed that social media political efficacy was positively related to successful experiences using social media for activism. The relationship between social media political efficacy and social media activism was stronger than that between the concept of political efficacy employed in prior research and social media activism. Theory and social media activism implications are discussed.