Non-equilibrium molecular dynamics software was developed to study thermal transport at the nanoscale. Lennard-Jones parameters of pure argon (mass and bond strength) were systematically modified to create heterogeneous thin film systems, including layered systems and nanocomposites, to investigate the influence of interfaces on thermal conductivity. Results were analyzed using combinations of kinetic theory and a thermal resistance network model together with the acoustic mismatch model (AMM). The introduction of a second material into an argon film generally decreased its overall thermal conductivity. Moreover, the presence of a nanoparticle was less influential in reducing thermal conductivity than the addition of a thin layer. (c) 2006 Elsevier Ltd. All rights reserved.