AbstractIt is intuitively felt that ambiguity plays a crucial role in human beings' everyday life and in psychologists' theoretical and applied work. However, ambiguity remains essentially non-problematised in psychological science since its foundation. This article analyses positivist and social constructionist perspectives on ambiguity in the context of their epistemological and ontological fundamental assumptions. The relational thesis of social constructionism is further analysed and it is argued that it constitutes a “weak thesis” concerning the relational constitution of human beings. In the second part, a dialogical alternative is elaborated. In this perspective, ambiguity is placed in the context of relationship and both are brought to an ontological ground. Therefore, it is argued, ambiguity is a fundamental property of human experience and plays a fundamental role in the constitution of (inter)subjective processes. The impact of this thesis on dialogical perspective on self is elaborated.