Far more long before the “interdisciplinarity” as a concept, become a prominent issue in scientific and philosophical developments, many thinkers and philosophers have investigated interdisciplinary. Erich Fromm is one of the distinguished contemporary intellectuals who have applied interdisciplinarity as the way of investigation. Here, we attempt to follow interdisciplinarity and border-crossing in his works. Studying social and political crisis of the modern society, Fromm realized that it is rooted in human’s psycho-existential characteristics on the one hand, and the socio-political status of the modern society on the other; which only “love” and “creative work” can treat. In Fromm’s view, neither political nor psychological analysis can offer a comprehensive understanding of what is going on in the society; rather a combination of the two. Thus, he believes in the necessity of border-crossing. “Love” as the “psycho-political” is the core of Fromm’s interdisciplinary study of the modern society.