This manual is intended for personnel involved with the sampling, analysis, and evaluation of crude oils after they are produced and stabilized. This comprises operators of pipelines, tankers, and storage terminals, laboratory personnel responsible for its characterization, refiners that eventually process it, and traders responsible for its purchase or sale. Crude oils are the most complex of petroleum streams. They are inhomogeneous and contain thousands of compounds that include hydrocarbons, heteroatomic compounds of nitrogen, sulfur, oxygen, and numerous other elements, sediment and water, and waxes. Sampling is a critical issue easily affected by their inhomogeneity. An inspection analysis can involve determining a few whole crude properties such as API gravity, sulfur, and sediment and water. Or the analysis can be very comprehensive, involving a fractional distillation that separates the crude oil into cuts or fractions of differing boiling ranges. This is followed by a detailed evaluation of the fractions to determine a number of properties and their conformance to product specifications or suitability for refinery upgrading processes. Many of the tests routinely used to characterize crude oils were not developed for this purpose and may not even include crude oil in the scope. Different streams may not be compatible when commingled during transportation or temporary storage, and precautions must be observed in mixing them to avoid potentially serious problems such as emulsion stabilization or asphaltene precipitation. Crude oils may also be used directly as a fuel in thermal power plants, but care must be exercised in selecting only those that will not have deleterious effects on the equipment or result in atmospheric emissions that exceed permitted levels. With the complexity in composition and the ever increasing number of new streams, especially those derived from oil sands, shale formations, and extra heavy oils, the analyst and refiner need rapid, reliable, and increasingly complex analytical techniques to characterize these accurately and in a timely manner.