The application of molecular mechanics calculations to the study of solid state organic photoconductors has been investigated. Using X-ray crystallographic information for a series of four N.N′-dialkylperylene pigments, 1–4, lattices of these molecules were modelled using the Dreiding force field. Comparison of the resulting lattices with the experimental data demonstrated that both molecular and physical features of the perylenes could be accurately reproduced in these calculations. When systematic deviations in molecular geometry occurred, these errors could be attributed to the generic nature of the force field. We have extended the computational studies to the problem of polymorphism since this is known to have a profound effect on photoconduction. To model enthalpic polymorphs of N,N′-dimethylperylene, 1, the symmetry relationships and atomic coordinates from the crystal structure of N,N′-di-n-pentylperylene, 4, were utilized. By truncating the pentyl substituents to methyl groups and applying external stresses to the resulting lattice during minimization it was possible to identify two likely polymorphs of 1. The inclusion of Gasteiger's partial equalization of orbital electronegativity (PEOE) charges on the perylenes was not found to be beneficial in locating suitable polymorphs. These computational methods have been successful in modelling perylene pigments in the solid state and have been shown to be useful in investigating polymorphism.