The concept of contraction was widely used in scholastic theories of individuation. Hence Bruno’s use of this concept within this particular philosophical field does not in itself allow us to identify his sources. There are, however, a number of external and internal relations between Bruno’s philosophy, in particular his theory of individuation, and the scholastic tradition concerning the Liber de causis. These relations have not yet been explored in the literature on Bruno, although they may shed some light on his use of contraction as an ontological concept. In this chapter I shall outline the historical background of the Liber de causis, present its central ideas, and explain how the term ‘contraction’ was used in its scholastic commentaries. I shall suggest that this scholastic tradition may well be one of the important sources to Bruno’s ontological concept of contraction.