Research and policy circles often emphasize the importance of social capital in achieving social transformation and economic development. There is also, however, potentially a 'dark side' to social capital. This study investigates the relationship between two different types of social capital-structural and cognitive-using two different measures of political violence: self-reported support for political violence and self-reported participation in political violence. We theorized that cognitive social capital will facilitate social cohesion within a community, enabling particularized trust between neighbours and a shared identity. On the other hand, structural social capital, or associational membership, potentially facilitates the diffusion of grievances and facilitates collective mobilization. Accordingly, we predict that higher levels of structural social capital will be associated with support for and participation in political violence, whilst higher levels of cognitive social capital will be associated with less support for and participation in political violence. We then test these predictions using Afrobarometer data on 40,455 individuals living in 27 African countries. Multivariate regression analysis confirms that indicators of structural and cognitive social capital have contrasting relationships with support for and participation in political violence. While particularized trust and national identity are negatively associated with political violence, religious and community associational membership are positively associated with political violence. In addition, we find that strength of attachment to a social identity, regardless of whether to an ethnic or national identity, is an important indicator of political violence.