Technical Abstract: This paper is Part 2 of the Series of articles on Nutritional Metrology: The Science of Nutritional Measurements. Accuracy based measurement systems lead to measurement compatibility. An idealized systems approach to development of accuracy based measurement includes a hierarchy of method and development linked to national or international recognized fundamental standards. Appropriate, well characterized reference materials provide the link between expensive, elaborate "definitive" methodology and cheaper, non-sophisticated "field" or methodology applied for routine applications involving large numbers of samples. Accuracy based measurement systems are in place and maintained for clinical chemistry and environmental measurements. For food analysis of nutrient content and microbiological food safety measurements there is no focused responsibility for maintaining or monitoring the accuracy and precision of the overall measurement systems. The traditional approach to food analysis focuses on the "process", i.e. use of official methods and their proper Quality Assurance practices. The metrological approach focuses on the "results", i.e. the accuracy of the data generated by a specific application of the method. Use of reliable, dependable tested methodology along with demonstrated performance on independent samples of known content linked to primary certified reference materials, allows an accuracy based system to be established.