Extrusion processing has been utilized for creating textured substrates for many years. Early extrusion systems relied on simple ingredients and equipment, but the demand for high-quality consumer goods has increased the range of raw materials that can be used, and the complexity of extrusion processes has changed dramatically. Today, there are three primary extrusion-based methods utilized for production of texturized proteins: dry extrusion, wet extrusion, and thermal extrusion. This article examines the basic principles of each process, outlines differences in the processes used in creating a textured substrate, and describes the limitations and challenges of each method.