Particle characterization is the necessary measurement of particulate systems to optimize process control and final product quality. Historically, particle characterization has been performed by a number of different technologies, providing a single size parameter. The most recent technology, three-dimensional image analysis, measures and reports a number of different sizes, and more significantly, shapes, greatly enhancing the understanding of all the important characteristics of particulate systems. This new insight leads to the ability to make process changes that deliver a product which provides the most desirable combination of both size and shape of the final particles. For example, flowability can decrease as a function of a change in length, an increase in aspect ratio, or an increase in surface roughness. Knowing the cause leads to a solution. And three-dimensional analysis adds the third dimension, thickness, to the arsenal of understanding and, significantly, to the accuracy of every parameter.