Fieldwork, the study of something in the natural environment where it occurs or that it inhabits, may be one of the oldest forms of human inquiry. Ancient scholars like Thucydides in Greece and Sima Qian in China studied events as close to firsthand as possible, reflected on them, and interpreted them. These are the basic elements of all fieldwork. Fieldwork traditions form the foundations of disciplines such as biology, botany, astronomy, geology, anthropology, and sociology. In this chapter, we discuss ethnography and participant observation, the two field traditions that developed from anthropology and sociology and that have been elaborated and refined by scholars in other human and professional sciences.