Wittgenstein's 'plan for the treatment of psychological concepts' in the second volume of his Remarks on the Philosophy of Psychology (§§63, 148) is often understood as motivated by purely classificatory concerns that have little philosophical significance. I argue that this is a misinterpretation of Wittgenstein and that his planned and partly realized 'treatment of psychological concepts' deserves a better fate. In the first part of the paper I attempt to show that Wittgenstein's interest in psychological concepts in RPPII, far from being merely an interest in their classification, is in fact closely connected to one important element of his conception of philosophy in the Philosophical Investigations, the requirement that 'all explanation must disappear, and description alone must take its place' (PI §109). In the second part of the paper I present the broad outlines of Wittgenstein's new, post-Investigations treatment of psychological concepts, as they are seen both in the account of the concepts directly addressed in RPPII §§63, 148 (those of seeing and other sense-impressions, of sensations, mental images and emotions), and also elsewhere in that volume where other important psychological concepts are discussed, e.g., those of thinking, intention and states of mind (Seelenzustande). Although it represents work in progress that was never brought to completion, I suggest that the account of psychological concepts in RPPII is an original, insufficiently appreciated strand of thought within Wittgenstein's oeuvre, and also that it is an account worth exploring for anyone not convinced by the scientism accepted by so much of the recent philosophy of mind.