Early police ethnographies suggest that officers are shaped by the colleagues around them. A common observation is that Officers’ workplace networks, including friendships and routine, day-to-day interactions are theorized to serve as key channels through which behaviors such as use of force spread. Yet few studies have directly traced the how these networks transmit force-related behaviors. To address this gap, we mapped the workplace friendship ties of more than 1,500 officers in a large US police department. We then asked whether officers’ firearm use is shaped by the colleagues they consider close friends. Longitudinal network models show that officers tend to adopt similar levels of firearm use to that of their workplace friends, even when accounting for individual characteristics and situational variables. These findings indicate that firearm behavior is shaped not only by personal attributes and work environments, but also by officers’ friendships.