In preparation for examining the place of introspective evidence in scientific psychology, the chapter begins by clarifying what introspection has been supposed to show, and why some concluded that it couldn't deliver. This requires a brief excursus into the various uses to which introspection was supposed to have been put by philosophers and psychologists in the modern period, together with a summary of objections. It then reconstructs some actual uses of introspection (or related techniques, differently monikered) in the early days of experimental psychology. It distinguishes broader and narrower conceptions of introspection and argues that recent critics have tended to misdescribe how introspection was supposed to work. Drawing upon the broader conception of introspection, it argues that introspective reports are ineliminable in perceptual psychology. It concludes with some examples of such ineliminable uses of introspective reports in both earlier and recent perceptual psychology.