This article first outlines the importance of Brentano’s doctrine of inner perception both to his understanding of the science of psychology in general in his Psychology from an Empirical Standpoint (1874) and to his new science of descriptive psychology in particular which he later advances in his lecture courses on ‘Descriptive Psychology’ at the University of Vienna in the 1880s and early 1890s. It then examines Husserl’s critique of that doctrine in an ‘Appendix: Inner and Outer Perception: Physical and Psychical Phenomena’, which Husserl added to the 1913 re-issue of his Logical Investigations (1900–01). This article argues that, though Husserl promotes a very different method in phenomenology to the method of ‘inner perception’ which Brentano designs for descriptive psychology, one cannot fully understand the significance of the method that Husserl advocates in phenomenology, both in the Logical Investigations and in Ideas I (1913), without (1) distinguishing four different meanings for ‘inner perception’ (as accompanying inner percept, inner reflection, incidental awareness, immanent perception) in Brentano’s thought and addressing (2) the problematic issue of the particular kind of scientific method for his new science of descriptive psychology which Brentano bequeaths to Husserl.