Why would you ever want to rely on electronic sensors when you can collect rich data like these by watching wild primates as they go about their daily lives? Compared to other mammalian species, primates are quite amenable to observational study; most species are diurnal and habituate quickly to the presence of human observers, allowing researchers to directly record data on their behaviors, movements, and interactions. Because, as primatologists, we can directly observe the behavior of our study animals in their natural habitats, we have never relied as heavily on telemetry (i.e., remote data collection) as scientists studying the behavior and ecology of other wild animals. Thus, before launching into specifics about how to GPS-track primates, it is worth asking why (or when) it would ever be worth the expense and the risk (to both the health of the study animal and the researcher) to catch and tag a primate with an electronic monitoring device. There are at least four distinct answers to this question.