Localized molecular rearrangements are widely regarded as the fundamental mechanism of shear-yielding plasticity in glassy polymers [1]. However, experimentally resolving both the atomistic details of these events and the associated continuum-scale (mesoscale) stress and strain fields is difficult. Building on Argon’s original concepts of shear transformation zones (STZs) [1], advanced STZ-based continuum models, which are commonly solved numerically using FEM, can reproduce macroscopic stress–strain curves, yet rely on assumptions and parameters that are difficult to assess experimentally [2]. The understanding of the quantitative impact of the chemistry-specific, atomistic mechanisms on the continuum scale remains incomplete. Here we present a multiscale approach combining molecular dynamics (MD) simulations and STZ-based continuum modeling to help address this gap for an industrially widely used epoxy thermoset formulation. The MD model employed is based on MD studies reported in the literature [3] and reproduces key mechanical properties of epoxies, such as elastic constants and yield stress, without fitting to those quantities. We present a simulation study of virtual shear tests that are used to extract continuum-relevant parameters and mechanistic descriptors from the atomistic description that are not directly accessible experimentally. These include quantities such as STZ volume, critical shear stress, and eigenstrain. For comparison, a STZ FEM model [3] is reformulated within the finite-strain framework of DAMASK and solved using an FFT-based spectral solver. Fitting the STZ model to macroscopic experimental data, STZ specific parameters are obtained and compared to the MD derived counterparts. The MD model may be a valuable pathway to reduce phenomenological fitting, improve the understanding of chemistry-specific yielding mechanisms in epoxy thermosets and provide a holistic model bridging scales. [1] A.S. Argon, The physics of deformation and fracture of polymers, Cambridge, Cambridge University Press, 2013. [2] F. Van Loock, L. Brassart, T. Pardoen, Implementation and calibration of a mesoscale model for amorphous plasticity based on shear transformation dynamics, International Journal of Plasticity, 145, 103079, 2021. [3] G. M. Odegard, S. U. Patil, P.P. Deshpande, et al., Molecular Dynamics Modeling of Epoxy Resins Using the Reactive Interface Force Field, Macromolecules, 54 (21), 9815–9824, 2021.