HELP is a two-dimensional, multimaterial, Eulerian Code for solving material flow problems in the hydrodynamic and elastic-plastic regimes. Although the code is basically Eulerian, material interfaces and free surfaces are propagated through the Calculation Mesh, in a Lagrangian manner, as discrete interfaces across which the materials are not allowed to interdiffuse. This interface treatment gives HELP a distinct advantage over other pure Eulerian Codes and allows it to be applied to the solution of a variety of complex, multimaterial problems. The basic HEPL techniques have been exercised over a wide range of solutions including hypervelocity and ballistic impact, fragmentation munitions, shaped charge jet formation, and shaped charge jet penetration. Considerable confidence has been gained in the basic numerical model.