This Part I of a journal article on youth gangs and police gang units includes a sociological analysis of the formation and function of gangs in neighborhoods where the socializing institutions of family, school, and community organizations have disintegrated under economic pressures and dysfunctional behaviors. Gangs become the coping and survival mechanism whereby the needs for acceptance, recognition, and security are met, albeit in partial and misguided ways. The author reports on her observation and perceptions of a car stop by a gang unit. In this stop and others she has observed, there has always been an event that triggered the stop, such as erratic driving, a passenger seen with a gun, or a vehicle fitting the description of one observed by a witness at the scene of a crime. The gang unit on patrol was aware that on previous nights there had been fights among youth in the area, with some girls accosted. The officers were on the scene to intervene, if possible, before a situation escalated. The car stopped on this occasion had been observed moving at a very slow pace down back streets and through parking lots, apparently paying attention to unoccupied, parked cars. The license number of the car was noted and checked, revealing that the owner was wanted on a warrant. The gang unit decided to stop the vehicle without waiting until its occupants broke into a parked car, which appeared to be their intention. This was an instance of proactive policing based on reasonable suspicion that a crime was about to be committed and that one of the occupants of the car was under an arrest warrant. This gang unit is committed to protecting the people of this neighborhood where gangs often threaten the safety of residents, without engaging in unreasonable proactive interventions. 8 notes