Stop and frisk is a proactive policing strategy that is widely used by police departments across the globe. In the United States, the origins of stop and frisk are rooted in the English practice of allowing night watchmen to stop and question individuals who were deemed suspicious. This ability to stop and question suspicious individuals serves two primary purposes. First, it gives law enforcement officers the ability to identify individuals who are looking to engage in criminal activity, stop those individuals, and prevent them from committing a criminal offense. Second, it may have a deterrent effect if potential offenders refrain from criminal offending because they do not want to risk being stopped. By the early 20th century, the implementation of stop and frisk in the United States varied by state. The Uniform Arrest Act, proposed in 1942, sought to standardize the practice. While several states adopted the Uniform Crime Act, which stipulated the circumstances under which a stop and frisk could occur, most states failed to do so. The practice of stop and frisk also faced constitutional challenges, with plaintiffs alleging violations of the Fourth Amendment’s prohibitions against unreasonable searches and seizures. In 1968, the US Supreme Court affirmed the constitutionality of stop and frisk. When law enforcement officers can establish reasonable suspicion, they can stop and question an individual. If there is reasonable suspicion to believe that a stopped individual possesses a weapon or poses a threat, law enforcement officers can also conduct a frisk. Stop and frisk has faced significant criticism and has been the subject of several class-action lawsuits, particularly in New York City. First, there is significant concern that nonwhite pedestrians are more likely than white pedestrians to be stopped, frisked, and subjected to the use of force. Next, stop and frisk may reduce perceptions of legitimacy and trust in law enforcement. The practice may also have adverse health consequences for those who are subjected to it or are in fear of being subjected to it. Finally, it is unclear whether stop and frisk prevents crime. It is also important to note that stop and frisk faces these same criticisms in other nations. The literature cited in this article summarizes key pieces on stop and frisk.