The concept of meaning plays a major role in Niklas Luhmann’s theory of social systems. Various aspects of meaning are briefly discussed here: the distinction between psychic systems and social systems, both defined as meaning-constituting systems, the three dimensions of meaning and, finally, the process of generalisation of meaning leading to the emergence of expectations and structures. Elements from phenomenology and hermeneutics are also quoted in an attempt to shed more light on Luhmann’s vocabulary and to examine how Luhmann used some of the insights gained through these theoretical perspectives to describe in his own way the operations of meaning-constituting systems.