The main thesis of this dissertation is that final causes are beings of reason (‘entia rationis’) in the philosophy of Francisco Suárez (1547-1617). The rejection of final causes is often seen as one of the hallmarks of Early Modern philosophy, marking the transition from an earlier Aristotelian tradition. However, in this dissertation it is shown that final causes had a problematic position already within the Aristotelian tradition. Although other examples of this can be found, this dissertation centers around the thinking of the philosopher and theologian Francisco Suárez and his treatment of final causes in his Disputationes Metaphysicae from 1597. Suárez counts final causes as one of the four kinds of causes, in line with the Aristotelian tradition. However, what these are and how they cause is, at closer inspection, not at all clear, as Suárez shapes his notion of final causation against the background of a definition of causation where efficient causation is the principal kind of causation. Due to this basic view on causes, he is faced with a host of problems when it comes to “salvaging” final causes. Though at first sight seemingly real, in a final analysis final causes are shown to belong to the class of “beings of reason,” ‘entia rationis,’ which are not real beings at all. However, it is also argued that this does not in itself preclude counting final causes as causes; something can really be a cause without being real. Chapter one presents Suárez’ general view on causes and causation. Chapter two presents his view on final causation. Chapter three examines the close link between final causation and moral psychology. Chapter four relates the question of final causation to God’s concurrence with the world. Finally, chapter five argues for the thesis that final causes are beings of reason.