Abstract: The child monitoring system that is composed of a portable detector that detects the passage of a child or an adult through a linear perimeter and a receiver that receives an alarm from the portable detector. The detector is programmed to transmit an alarm when the detector detects a child has passed through the linear perimeter and the detector does not detect an adult passing through the linear perimeter within a period. If the system detects that a child has passed through the linear perimeter, then the system is programmed to determine if an adult has also passed thought the linear perimeter, if no adult passes through the linear perimeter within a period, then the detector will transmit a transmission to a wireless receiver that will alarm a caregiver of the child that the child has left the secured area.