Description of TEPOP (Tracking Error Propagation and Orbit Prediction Program), a RAND-modified FORTRAN IV program used in the AFSC/ADC Joint Mission Analysis on Surveillance of Objects in Space. TEPOP simulates space-vehicle tracking data from as many as 54 sensors. RAND improvements: Sensors may be satellite-based, may rotate, may be limited in azimuth, elevation, and range; drag bias can be included; the JPL ephemeris tape is used; and the program was converted to double-precision. Besides determining a target's path from real data, TEPOP can be used to generate synthetic data for objects orbiting earth, sun, moon, Mars, Venus, or Jupiter, or on an interplanetary course; to study the effects of introducing random and systematic errors; and to generate confidence regions for position and velocity. The reference coordinate system is automatically centered on whichever body influences the tracked object at the time.