Inspired by Aristotle, Franz Brentano revived the concept of intentionality to characterize the domain of mental phenomena studied by descriptive psychology. Edmund Husserl, while discarding much of Brentano?s conceptual framework and presuppositions, located intentionality at the core of his science of pure consciousness (phenomenology). Martin Heidegger, Husserl?s assistant from 1919 to 1923, dropped all reference to intentionality and consciousness in Being and Time (1927), and so appeared to break sharply with his avowed mentors, Brentano and Husserl. Some recent commentators have sided with Heidegger and have endorsed his critique of Husserl and Brentano as still caught up in epistemological, representationalist approaches to intentionality. I argue that Heidegger is developing Husserl, focusing in particular on the ontological dimension of intentionality, not reversing or abandoning his account. Heidegger?s criticisms of representationalism merely repeat Husserl?s. Furthermore, I argue that Husserl?s account of cognitive intentionality, which recognizes the importance of the disinterested theoretical attitude for scientific knowledge, has been underestimated and misunderstood by Heidegger, who treats scientific cognition as a deficient form of practice. In short, Heidegger is more dependent on Husserl than he ever publicly acknowledged.