The origins of object theory in the philosophical psychology and semantic theory of Meinong and the Graz school he fledged can be traced both to the insight and failure of Brentano's immanent objectivity or intentional in-existence thesis. The immanence thesis is documented, together with its critical reception in Höfler's Logik, Twardowski's Zur Lehre vom Inhalt und Gegenstand der Vorstellungen, and Meinong's earlier writings and mature Gegenstandstheorie, in which immanent thought content and transcendent intentional object are distinguished. Brentano's thesis of immanent intentionality as the mark of the mental is reinterpreted to imply that only content is the immanently intentional component of presentations. Brentano's thought from the early immanence thesis through the so-called Immanenzkrise and his later Reismus is explored against the background of his students' reactions to the original 1874 intentionality thesis and its idealist implications, in the emergence of Meinong's object theory and Husserl's transcendental phenomenology. Finally, Brentano's reism in the later ontology is critically examined, as his solution to ontic problems of immanent intentionality, limiting intentional objects to transcendent concrete particulars, as contrasted with Meinong's object theory.