This study evaluated a police-led community initiative that combined various enforcement and prevention efforts to reduce gun violence and other violence in a selected area of St. Louis, Missouri. A quasi-experimental multiple time-series design was used to compare trends in total violence and gun violence in the program neighborhood with the average of these trends in seven matched comparison neighborhoods. Total violence and gun violence declined in the program area relative to trends in the comparison areas during the 9-month program period, and these reductions seemed to be most strongly associated with the program’s heightened enforcement efforts. However, the results were not sufficient to conclude that the program had statistically significant effects beyond its early weeks when enforcement efforts were most intensive and total violence declined significantly. This study adds to the limited evidence based on comprehensive, criminal justice-led initiatives to prevent violent crime, including gun offenses. We suggest that programs like those in St. Louis might be refined through further emphasis on formalized problem solving, high-risk groups, hot spot locations, community participation, and project maintenance.