The objective of this research is to describe the effect of the 911 emergency telephone number in Dade County, Florida. The study will identify delays in dispatching before and after the implementation of the 911 System and determine the relationship of these delays to the outcome of cardiac arrests. Since survivorship is known to be highly time-dependent for cardiac arrest victims, this population provides a sensitive group in which to measure the relation of dispatch delays and to explore its relationship to outcome in terms of survivorship. Information on the delay in dispatching appropriate emergency medical personnel will be abstracted from the alarm reports of an identified population of individuals known to have received prehospital cardiopulmonary resucitation. The research will describe the emergency dispatch system for seven-month periods before and after implementation of the 911 System.