Despite the need to prepare engineers for leadership in the workforce, the civil engineering curriculum lacks formal leadership education. The limited focus on leadership in the curriculum raises questions of how and where students are developing leadership competencies. Social capital, the resources embedded in an individual's social network, may play a significant role in the development of students' leadership competencies. Yet little is known about how civil engineering students access and activate their social networks and what leadership-related benefits social capital provides. Using an asset-based approach and applying social capital theory, the present research investigated the role of social capital in leadership development of civil engineering undergraduates. In 14 semistructured interviews with students across the US, students identified several sources of social capital in their social networks. Students activated this social capital through observation and conversation with industry mentors, peers, family, and faculty; participation in out-of-class activities; and identification of leadership roles they could take on. Recommendations based on this work include facilitating safe and welcoming spaces where students can approach civil engineering faculty members and industry professionals with questions about their careers and futures.