All communities developed their bodies of knowledge about the environment in which they lived; these involved the knowledge of animals, plants, and land, and also the continuously growing knowledge of the best ways to obtain benefits from the environment, in terms of food, shelter, medications, and many other commodities. The indigenous practices were usually sustainable, because preserving the species that provided food and other benefits was an easily recognizable necessity. The knowledge was also holistic and, therefore, inherently multidisciplinary. The present chapter offers an overview of traditional and indigenous knowledge (ethnosciences), mostly analyzing it in terms of modern disciplines to facilitate readability, while taking care of highlighting multidisciplinary contributions and routes. The importance of indigenous knowledge for the design of sustainable options-as needed under current global circumstances-and the corresponding importance of multidisciplinarity are emphasized, and practical details are outlined.