The development of substorm activity at synchronous orbit (6.6 RE) for multiple-onset substorms was studied by using the energetic particle and magnetic field data in three local time groups (the afternoon region, the premidnight region, and the postmidnight region). The geostationary spacecraft 1976--059 and 1977--007 provided the measurements of 30- to 2000-keV electrons and 145- to 560-keV protons, GMS the measurements of >2000 keV electrons, and GOES 1 and GOES 2 the measurements of the magnetic field. The ground magnetic variations in a wide area were examined to determine the general characteristics of substorm activity and the timing of various phenomena. The substorm evolutions showed a variety of forms at synchronous orbit, but they can be characterized by the following view: Substorm activity initially starts in a longitudinally limited sector that is situated in the premidnight region, and the effect of this activity is not seen in other regions. The activity then expands westward and eastward during a period of successive onsets. There is an indication that the westward propagation is faster than the eastward propagation.