Planetary Ephemeris Program (PEP) computes numerical ephemerides and simultaneously analyzes a heterogeneous collection of astrometric data. Written in Fortran, it is a general-purpose astrometric data-analysis program and models orbital motion in the solar system, determines orbital initial conditions and planetary masses, and has been used to, for example, measure general relativistic effects and test physics theories beyond the standard model. PEP also models pulsar motions and distant radio sources, and can solve for sky coordinates for radio sources, plasma densities, and the second harmonic of the Sun's gravitational field.