We report on the development and application of a silicon microdevice for the in situ quantitative mechanical characterization of single 1-D nanomaterials within a scanning electron microscope equipped with a quantitative nanoindenter. The design makes it possible to convert a compressive nanoindentation force applied to a shuttle to uniaxial tension on a specimen attached to a sample stage. Finite-element analysis and experimental calibration have been employed to extract the specimen stress versus strain curve from the indentation load versus displacement curve. The stress versus strain curves for three 200-300-nm-diameter Ni nanowire specimens are presented and analyzed.