It is generally acknowledged that it is principally due to Brentano and his students, in particular Husserl, that the medieval-scholastic terminology of ‘intentional act’ and ‘intentional object’ re-gained widespread currency in philosophical circles in the late-nineteenth and early-twentieth centuries. This paper examines Brentano’s original re-introduction and revaluation of the Scholastic concept of intentionality into a root-concept of descriptive psychology. It concentrates on (1) Brentano’s modification of the Scholastic concept of object-relatedness of the will to depict the object-relatedness of all psychical-act experiences in consciousness, (2) Brentano’s modification of the Scholastic concept of the abstracted form of sense residing intentionally in the soul of the knower to depict the directly intended object of consciousness, and (3) the significance of these modifications for understanding what commentators now call ‘Brentano’s thesis’. It notes that Brentano develops not one but two descriptive-psychological theses of intentionality both of which are entirely unScholastic. It also notes, however, that part of the original meaning of the metaphysical distinction that the Scholastics drew between ‘intentional indwelling’ (inesse intentionale) and ‘real being’ (esse naturale) continues to play a critical role in Brentano’s revision of the concept of intentionality in Psychology from an Empirical Standpoint (1874) and in his lecture courses delivered at Vienna University on Descriptive Psychology (1887-91), and that this part of the original meaning of the Scholastic concept of intentionality remains both alive and intact in Brentano’s 1874 study and in Husserl’s (in)famous transcendental reduction of Ideas I (1913). Thus the paper argues that identifying what Brentano accepts, rejects, and adds to the original Scholastic concepts of ‘intentional act’ and ‘the intentional indwelling of an object’ cannot be evaded in the proper elucidation and evaluation of ‘Brentano’s thesis’.