In 1888, he founded the La Plata Museum of Natural History, the most important of its kind in South America. The scholar Jens Andermann has studied how Moreno's collection of artifacts at these two museums helped establish Argentine history, and the government's claim to its territory. Through these scientific and cultural collections, Moreno contributed to the national mythology. He brought artifacts and materials in from remote regions to be examined, catalogued and studies at the museum in the capital. Andermann has written that such museums of natural history and anthropology "enabled and justified state control of both the natural resources and indigenous populations of Argentina." They also helped develop the national narratives being shaped. Moreno served as the first Director of Museo de la Plata, guiding it until 1906.