The title Expert-by-Experience has been used frequently in mental health literature and policy making in recent years. The implication is that by virtue of suffering from a mental disorder, the person has access to a unique form of knowledge that would separate them from others, affording them the status of an expert. In this article, the concept is put under philosophical scrutiny. I use Wittgenstein's Private Language Argument and Ryle's work on introspection to show that personal experience could not be (...) a basis for expertise. Personal experience and introspection could not be a basis for knowledge underpinning expertise. (shrink)