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Recently, the Moderate Resolution Imaging Spectroradiometer (MODIS) Characterization Support Team (MCST) has worked closely with the science team members to make significant improvements in both Terra and Aqua MODIS sensors. These refinements are included in the newly released Collection 6 (C6) Level 1B (L1B) products, and they primarily mitigate the long-term drifts observed in the short-wavelength bands of the MODIS sensors. This letter focuses particularly on evaluating the improvement in the long-term on-orbit radiometric calibration stability of the Terra MODIS sensor by comparing the trends with the Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) sensor. In this study, Terra MODIS L1B products from both Collection 5 (C5) and C6 were used to compare the long-term top-of-atmosphere (TOA) reflectance trending of the Terra MODIS reflective solar bands (RSB) with spectrally matching bands of the L7 ETM+ sensors over the Committee on Earth Observation Satellites (CEOS) reference pseudo-invariant calibration sites (PICS). In addition, intensive statistical tests were performed to support the assessment of the observed long-term drifts. The results from the newly processed Terra MODIS C6 L1B products clearly show the excellent calibration stability (long-term drift within 2%) of the MODIS sensor with the multi-year drifts within the specified calibration uncertainty.