Compositions and methods for substantially uniformly dispersing fibers throughout a starch-based composition. The fibers are dispersed throughout the composition by means of a high yield stress, high viscosity fluid fraction formed by interacting together water and a thickening agent such as gelatinized starch. The well-dispersed fibers provide for a large variety of processing conditions in the manufacture of articles from such starch-based compositions (e.g., greater variations in the use of water, the amount of water that must be removed to yield a form stable article, and wall thickness). Articles formed thereby have greatly improved mechanical properties as a result of the reinforcing effect of the uniformly dispersed fibers. The fibers preferably have an average length of at least about 2 mm and an aspect ratio of at least about 25:1. Other admixtures may be added to the starch-based compositions upon dispersing the fibers, such as ungelatinized starch, rheology-modifying agents, mold-release agents, inorganic fillers, hydraulically settable binders, plasticizers, integral coating or sealing materials, and dispersants.