Plasma-facing materials (PFMs) in future fusion devices will be exposed to demanding operating conditions involving high heat fluxes, aggressive particle and neutron fluxes, and high stresses.  Although tungsten has emerged as a promising candidate, there are several outstanding issues yet to be resolved, including high temperature stability, mechanical performance, and radiation tolerance.  The aim of this research is to address these limitations in tandem by precisely tailoring the volume fraction, chemistry, and structural state of grain boundaries in tungsten.  These novel materials, known as solute-stabilized nanostructured tungsten alloys, will be designed and screened through thermodynamic modeling coupled with in situ electron microscopy experiments.  Select alloys will then be scaled via powder metallurgy processes to synthesize bulk materials for mapping structure-property-performance correlations.  The insights established through this research will markedly enhance the state of tungsten alloys for fusion applications and, in turn, provide opportunities to validate their performance under relevant PFM conditions.