In-situ diffraction experiments were performed with high-energy synchrotron X-rays to measure strains In. crystalline reinforcing particles (5 and 10 vol. pct W or 5 vol. pet Ta) of bulk metallic glass composites. As the composites were subjected to multiple uniaxial tensile load/unload cycles up to applied stresses of 1650 MPa, load transfer from the matrix to the stiffer particles was observed. At low applied loads,.where the particles are elastic, agreement with Eshelby elastic predictions for stress partitioning between matrix and particles is found, indicating good bonding between the phases. At high applied, loads, departure from the elastic stress partitioning is observed when the particles reach the von Mises yield criterion, as expected when plasticity occurs in the particles. Multiple mechanical excursions in the particle plastic region lead to strain hardening in the particles, as well as evolution in the residual strain state of the unloaded composite.