A wide variety of analytical methods have been developed for performing targeted metabolomics. By combining multiple analytical techniques, it is now possible to achieve much more comprehensive coverage of the metabolome. We combined multiple analytical techniques to comprehensively and quantitatively characterize the widely studied NIST human plasma refer-ence material SRM 1950. Our goal was to provide a large, well-validated list of confident metabolite concentration values (i.e., benchmarks) to assist the metabolomics community in its calibration and comparison efforts. We used four different analytical platforms including high resolution NMR spectroscopy (700 MHz), direct injection tandem mass spectrometry (DI-MS/MS), liquid chromatography tandem mass spectrometry (LC-MS/MS) and inductively coupled plasma mass spectrometry (ICP-MS). A total of eight carefully validated analytical assays were run, yielding accurate quantitative measurements for 728 unique metabolites or metabolite species. In addition, computer-aided literature mining allowed us to identify another 330 unique metabolites previously identified and quantified in SRM 1950. We compared NIST certified values along with literature-derived concentrations/ranges to the metabolite concentrations measured by our four platforms and eight assays. From these high-confidence assays/platforms, we generated a list of high-confidence concentration values for a total of 1058 metabolites or metabolite species in SRM 1950. This includes concentration data for 60 amino acids and related compounds, 48 bile acids, 72 amines/sugars/alcohols, 21 metals, 8 cate-cholamines, 11 vitamins, 92 organic acids, 40 fatty acids/steroids/nucleobases/indole derivatives, 5 polyflourinated compounds, 7 carotenoids, 39 acylcarnitines, 76 oxylipins, 13 stereols and 566 lipids or lipid species. This data set represents the most complete quantitative characterization of the widely used human reference standard (SRM 1950). This list also provides 1058 high-confidence reference values for SRM 1950 that should allow other research labs to easily compare and calibrate their targeted and untargeted metabolomic assays. An online database (SRM1950-DB) containing the complete set of 1058 plasma metabolites or metabolite species in SRM 1950, their structures, HMDB IDs, mass (monoisotopic and average), chemical class, concentrations - with standard deviations, references or notes (on work-up methods) and reliability are freely available here.