A Cool Stop is a traffic stop based upon probable cause that a traffic violation has occurred, but with the ulterior motive of covertly gathering information needed in an ongoing criminal investigation, apprehending a suspect wanted for having committed an unrelated criminal violation, or investigating an unrelated offense. Because critical evidence can be uncovered without a warrant, Cool Stops are a valuable and effective investigative tool. However, circumstances involving those traffic stops are inherently much more complex than typical Cool Stops, as additional and significant issues related to protecting an ongoing investigation are involved. The article reviews legal considerations relative to Cool Stops and practical considerations relative to what the uniformed officer should know.