On March 1, 2005, the U.S. Supreme Court ruled that the execution of offenders under the age of 18 at the time of their criminal offense was unconstitutional. Although many welcomed this decision, some individuals still remain concerned that the elimination of the specter of capital punishment will inevitably increase homicidal behavior among juveniles by reducing the prospect of deterrence. Using monthly data from the Supplemental Homicide Reports and a multiple time-series research design, the authors investigate the impact of the Roper v. Simmons decision on homicides perpetrated by juveniles in the 20 states affected by the law. Maximum likelihood results reveal that the repeal of the juvenile death penalty has had no effect on juvenile homicidal behavior.