Two-dimensional semiconductors have unique optical, electronic, and transport properties that support compelling new functionalities attributable to atom-scale interfacial effects. However, the utility of two-dimensional semiconductors is constrained by limited tunability of their optoelectronic properties. Empirical enhancement of electronic and photonic properties of two-dimensional semiconductors via deposition of plasmonic nanoparticles has motivated examination of interactions between photon-induced optoelectronic resonance and modes on nanoparticles and electronic modes and nonlinear activity on monolayer semiconductor nanocrystals. To characterize the rapid, sub-bandgap optoelectronic interactions between nanoparticles and semiconductor nanoparticles, appropriate experimental and theoretical approaches are being developed. Electron spectroscopy and imaging, in conjunction with computational solutions to Maxwell’s equations, have emerged as methods well-suited to provide femtosecond and nanometer scale resolution needed to quantitatively characterize optoelectronic interactions at interconnective hetero-interfaces between nanoparticles and two-dimensional semiconductors. Nonlinear susceptibility and wavelength mixing of two-dimensional semiconductors and their enhancement by nanoparticle-supported resonances and modes is being evaluated using coherent optical, spectroscopic, and computational approaches. Increased understanding provided by such emerging instrumental and computational approaches supports design and development of atom-thin flexible integrated circuits, field effect transistors, and closed-loop resonators using tunable low power optoelectronic interconnects on two-dimensional semiconductors.