Peru ranks among the countries with the highest mammalian diversity in the world. This chapter traces the history of mammalogy in the country, beginning with Johann Jakob von Tschudi’s landmark 1844 publication on Peruvian mammals and extending through to the second decade of the twenty-first century. Over the past 25 years, the volume of research on Peruvian mammals has surged, largely driven by contributions from local scientists. As a result, the number of recognized mammalian species in the country has risen from 460 in 1995 to 573 in 2021. However, this rich diversity is severely threatened by the rapid degradation of natural habitats due to deforestation, agriculture, mining, and other human activities. A key challenge for Peruvian mammalogists today is leveraging the wealth of data accumulated in recent decades to inform targeted and effective conservation strategies.