?;?;A hierarchical multiscale modeling approach to characterize physical properties of nanoparticulate polymer composites is introduced. Due to the critically increased surface to volume ratio of nanoscale particles, elastic and thermal properties of p olymer nanocomposites show a prominent particle size dependency. Such an unusual evolution of the properties is related to the formation of densified polymer interphase zone right in the vicinity of nanoparticles. To capture these nanoscale effects in design and analysis of polymer nanocomposites, molecular dynamics have been widely applied. However, the molecular level simulations require excessive computation time and resources. Therefore, multiscale approach to hierarchically combine the molecular level simulation and conventional continuum mechanics-based analytical models has been spotlighted. In this presentation, the multiscale approach based on molecular dynamics simulations, micromechanics model based on Eshelby’s solution and mathematical homogenization method is briefly reviewed and perspective of the?future directions in this research field is discussed.