The theoretical basis for the rigid-body precession and nutation of Mars, including the contributions of Phobos, Deimos, and the planets, is determined. The total precession in longitude for a solid-core rigid Mars model is found to be -7.296 + or - 0.021 arcsec/yr. This precession includes the motion resulting from the extremely long-period (above 10,000 yr) nutation components that result from changes in Mars' orbit with time. These nutation components also contribute a 'precession' in latitude of 0.4255 + or - 0.0012 arcsec/yr. The nutation components in obliquity consist of six solar terms and one nutation term each from the motion of the nodes of Phobos and Deimos. The amplitudes and periods of the solar nutation terms are in agreement with the nutation found by Reasenberg and King (1979). A single nutation in longitude driven by Jupiter is the only significant planetary contribution at the milliarcsecond level.