A classical mechanical theory for the scattering of small, rigid molecules is developed which includes energy and momentum transfers between the surface and projectile for both translational and rotational motion. The results of calculations with this model are compared with recent high-precision measurements of the scattering of C2H2 from a clean, ordered LiF surface. The comparisons between calculations and measurements indicate that the observed angular distributions are dominated by single collisions with the surface and their shapes are due largely to translational energy (multiphonon) transfers. The calculated results for rotational energy transfer to the scattered molecules are also in reasonable agreement with measurements.