Abstract: The aim of this work is to propose a concept of threshold intended both as a line that separates and that, at the same time, unites and also as a place that defines the identity of something in relation to its diversity. In this regard, we will try to delineate what Waldenfels calls “a thought of the threshold”, that is a thought that tries to account for the question of otherness. We will analyze the figure of the foreigner in the thought of Simmel and Schütz and that of the stranger in the thought of Waldenfels. The thesis we want to sustain is that otherness does not come from an external dimension but from an internal dimension. In this way, it is possible to prepare policies of openness and welcome and to outline the physiognomy of a thought of hospitality and welcome.