Although law enforcement agencies arrest criminal group leaders to dismantle organized crime, few studies have assessed whether such interventions produce adverse effects. Through a mixed‐method comparative case study of the Latin Kings and 22 Boys street gangs in Chicago, this article examines the consequences of arresting a gang's leader. Using violent crime data, I show that a spike in violent crime took place in the first month after the arrest of the 22 Boys gang leader. In contrast, the arrest of the Latin Kings gang leader produced no change in violent crime. Using several qualitative data sources, I show that the arrest of the 22 Boys gang leader temporarily led to the gang's withdrawal from its territory, which spurred violent aggression from rival gangs in adjacent territories. In contrast, the Latin Kings gang continued its operations because the gang's prison leaders quickly appointed new leadership. The results suggest that criminal group embeddedness (or the social relations between criminal groups) can contribute to adverse effects in interventions targeting gang or other criminal group leaders.