Mammalogy in El Salvador started in the nineteenth century, with a few specimens being collected by marine captains, which led to foreign naturalists and zoologists visiting the country, beginning the first synoptic collection of Salvadoran mammals in the twentieth century. As surveys started, the creation of checklists also began, especially in regard to land mammals; thus, the world and the new, emerging contingent of Salvadoran biologists came to know more and more about the biodiversity housed in the relatively small country. This knowledge increased between 1920 and 1970, at which point the nation fell victim to social struggles, culminating in a civil war that began in 1980 and lasted for over a decade, one byproduct of which was the almost complete cessation of scientific research in the country. Nevertheless, in the 1980s, although it was dangerous to go out and collect, James G. Owen, a mammalogist from the United States, began to collect more mammalian specimens, which enabled him, in 1991, to update the previous checklist published in 1961. With the Peace Agreements established in 1992, studies in mammalogy once again started to thrive, with the nation’s own mammalogists showing more leadership during the following decade. Furthermore, in the new Millennium, Salvadoran mammalogy started to grow beyond checklists to focus on more specialized research, such as ecology and population genetics, thus anticipating the use of mammals as models for solving questions about landscape fragmentation, which is one the main problems in a small territory where scarce forest patches still remain.