Nonpolar crystals must exhibit a surface polarization induced by the loss of bulk symmetry at the surface. For crystals of nonpolar molecules, the surface polarization is normally induced by incomplete cancellation of the electric fields of the molecular quadrupole moments; for crystals of polar molecules, it is produced by incomplete cancellation of the electric fields of the molecular dipole moments. Algebraic treatments are developed for both cases, including all local-field effects via planewise dipole sums. Surface piezoelectricity and pyroelectricity follow from the strain and temperature dependences of the surface polarization. Numerical calculations are presented in an accompanying paper.