Member Of Service (M.O.S.) is a term used in parts of the US for any first responder such as a police officer, firefighter, correction officer, emergency medical technician or paramedic.[1] Originally used as an exclusive term by the New York City Police Department, its use has expanded throughout the northeast to identify other types of emergency responders.[2] The term is primarily used to identify an emergency responder in need of assistance. The M.O.S. in question may have been in a motor vehicle accident, an assault or shooting.[3] The units responding usually get this information from their dispatcher after receiving a 911 or radio call for "M.O.S. needs help".