Although the study of mammals in Costa Rica started more than 180 years ago, there are very few publications that summarize it. Three periods in the history of Costa Rican mammalogy have been recognized: 1840–1890, 1890–1950, and 1950–2024. Before 1840, the only existing information came from writings by “travelers” and “naturalists” from the eighteenth century and part of the nineteenth century. The key event from the First Period is the publication of Alston’s book “Biología Centrali-Americana” (1879). Alexander von Frantzius’ and Karl Hoffmann’s work also stands out; both of them sent recollected materials to European museums to be identified. During the Second Period, the Museum of Costa Rica was created (1887), with Anastasio Alfaro serving as its first director and George K. Cherrie and Cecil F. Underwood as its taxidermists. In the Third Period, key developments included the establishment of national universities and various nongovernmental organizations, which drew many students and researchers, both local and international. Recent scientific output has predominantly been generated by foreign researchers, with a significant emphasis on ecology. Notably, the order Primates has seen the highest number of publications, particularly in the area of physiology. Although Costa Rica is a small country, it is considered to be one of the most studied countries in the world, and in recent years, Costa Rican scientific production has diversified and increased. There are still many areas that remain to be discovered and studied, especially in the low region of the South Pacific and in the highlands of Talamanca’s mountain range.