Post-September 11th law enforcement practices are a bit different than they were prior to the terrorist attacks. Law enforcement and other emergency response personnel have been training and preparing for future attacks. The blackouts in August 2003 provided valuable training opportunities and lessons for law enforcement and other emergency response agencies. The law enforcement response to the blackout and lessons learned from the experience in New York, Cleveland, Detroit, and New Jersey are discussed. Overall, the police agencies in New York, Cleveland, Detroit, and New Jersey report that they were prepared for many aspects of the emergency mobilization of police officers during the blackout. Police efforts during the blackout were extremely effective in terms of crime deterrence and control. The police departments were able to quickly dispatch large numbers of uniformed officers all over the city, particularly in high-crime areas. As a result of the police presence and training, all of the departments reported either having average levels of crime or less than average levels of crime during the blackout. On the whole citizens remained calm and officers effectively responded to the emergency. Some of the problems encountered during the blackout were isolated incidents of looting or breaking and entering; problems with water and food supplies; transportation problems especially in New York City; and problems with failing backup generators. The police departments commented that although they had prepared to provide food and water for at-risk citizens during an emergency, they had not thought about how to feed their own personnel. Thus, the blackout in 2003 provided valuable insights into gaps that may exist in emergency management plans and gave police departments and individual officers an opportunity to enact practices that they had been training for since September 11, 2001. A textbox included in the article offers the story of one New York City police officer during the blackout.