ABSTRACTIn the Time Service Department of the U.S. Naval Observatory, there are several operational programs that utilize time from the Global Positioning System (GPS) satellites in one form or another.1The monitoring of GPS time, derived from the ensemble of satellites, to ensure that it stays within one microsecond of the U.S. Naval Observatory Master Clock and to determine the quality of its performance between uploads.2The monitoring of the individual spacecraft clocks to determine their performance, both over the short term and the long term.3The monitoring of Coordinated Universal Time (UTC) as derived from GPS time in order to ensure that the accuracy of GPS as a time distribution system is good to 100 nanoseconds.4The performance of common‐view time transfers between the Naval Observatory and other worldwide laboratories, to monitor timescales and to investigate signal propogation through the ionosphere.This paper describes these four projects and discusses their importance to the Global Positioning System and to the world timing communit