Interlayer diffusion and interdigitation in Langmuir-Blodgett multilayers containing asymmetric interfaces between cadmium arachidate (CdA) and an octadecyl-substituted polyglutamate (PG) were studied using neutron reflectometry and X-ray reflectometry. It was found that the structure of the two-component CdA/PG multilayers is less stable to annealing than is the structure of multilayers containing only CdA or only PG. The PG side chains and CdA tails at adjoining layers appear to interdigitate significantly in unannealed multilayers, and this interdigitation becomes more mal ked after annealing.