George Oprescu, who at that time became a member of the Romanian Academy and director of the Institute of Art History, had organized in his institute a section of folk art, in which he welcomed several former students and collaborators of Dimitrie Gusti. Paul H. Stahl was appointed research scientist in this section and he thus had the opportunity to travel throughout the country and study folk art. He chose the peasant house as his main subject, that is, a field of study helping him to easily maintain a link with the understanding of the various aspects of social life and with what he had learned at college. Thus, for over twenty years, he traveled to the towns and especially the villages out in the country: the results of his studies appeared in a series of volumes that significantly enrich the knowledge of rural Romania and its peasant culture.
We recognize in these publications two of the ideas that stood central in all his activities: the desire to make the Romanian culture be internationally known and the idea that social facts should not only be examined statically but also with regard to their historical development. Thus, while the usually accepted classification divides the country into zones in which a single type of house appears, he divided the houses into evolving groups. The link to history, or more precisely with the idea of evolution, is evident; a summary appears in a volume published in Sibiu (Planurile caselor româneşti ţărăneşti, 1958).
Known for his works and especially for the interest that they aroused, Stahl was invited by Mihai Berza to lead the section “Ethnography, folklore, and art history” of the new Institute for South-East European Studies. There, his efforts to increase the visibility and international recognition of Romanian peasant culture became even more successful. To his interest in folk art, of the previous years, he added concerns increasingly oriented towards the social issues. The prohibition to publish a new volume and several articles, as well as the prohibition to take part in congresses and conventions held outside the areas under Soviet domination determined him to leave for France in 1969.
After a particularly difficult year (because of financial worries and problems), he was received by Fernand Braudel, to whom he presented a working program that concerned both history and sociology, namely a study of the relationship between the peasant culture and the culture of the boyars (upper nobility) and royal families during the last three centuries in South-Eastern Europe. Well received, he was, in 1970, appointed director of studies at the École des Hautes Études en Sciences Sociales (E.H.E.S.S.). Asked by Braudel to propose a title for the direction of studies that he was to lead, he suggested the title „Sociology of South-Eastern Europe”; Braudel however advised him to use the word „ethnology” in order to make the proposal more easily acceptable. Stahl, therefore, adopted this modified title for the direction of studies under his lead.
In the 1980s, he offered a new series of courses as part of a new seminar that he directed, the first one of its kind ever held at the E.H.E.S.S., and entitled „Legal Anthropology of Europe”. One year after, în 1971, he also start to teach at the Université René Descartes (Sorbonne). There he offered also a course on „The Anthropology of South-Eastern Europe”, but he remained mainly employed by the E.H.E.S.S..
, his old comparative concerns and his interest in history became the main axis of his orientation. The titles of his courses at the E.H.E.S.S., which varied every year, encompass a wide variety of topics from which the concerns for his origin country are never absent. At the Sorbonne he taught the same course for some years, but in 1981 he ventured to set up a new Section, called „Sociology and Ethnology of Europe”, which was the first of its kind in a French university.