His research focuses on the impact of violence and violent social structures on human flourishing. His book, Homies and Hermanos: God and Gangs in Central America (Oxford University Press 2011) takes a close-up look at the lives of sixty-three former gang members, many of whom joined an evangelical congregation as part of their attempt to extricate themselves from gang violence. He is currently conducting follow-up research to gauge the long-term impact of the decision to leave the gang by way of the church.