Polyester compositions comprising microfibers and micropowders are disclosed. The polyester compositions are made by contacting microfibers and micropowders with polymerizable components, such as monomers, suitable for making polyesters, and polymerizing the polymerizable components. The microfibers and micropowders can be provided in the form of either separate slurries, or a single slurry. The micropowders can also alternatively be provided in the form of a powder rather than a slurry. A slurry containing microfiber and micropowders, and a process for making such a slurry, is also disclosed. Incorporating microfibers and micropowders into a polyester improves the properties of the molded parts, films and/or fibers that are made from such a polyester. A slurry containing microfibers and micropowders is more stable and easier to process, wherein the micropowder is less likely to separate out of the slurry or agglomerate when compared to a slurry containing only micropowder.