NPL's holdings include extensive collections of invertebrate fossils and smaller but scientifically significant collections of fossil plants, gems, minerals, meteorites, and tektites. Most time periods are represented in the collection of almost 4 million fossil invertebrate specimens. Though the collection focuses on Texas and the USA, specimens are included from all over the world.
Numerous large collections are used for teaching and research. While focusing on Texas, most are essentially worldwide in scope. Vertebrate holdings include collections of fishes, amphibians, and reptiles. Birds and mammals were transferred to the collections at Texas-Tech. Invertebrate collections include fluid-preserved and dried, pinned insects, as well as cave-dwelling arthropods.
In addition to the collections amassed by its own faculty, staff, and students over many years of active collecting, the laboratory also holds collections originally made by various other units of The University of Texas at Austin, adopted collections from three other Texas universities, and collections made by several state and federal projects.