This article was commissioned as a supplement to theOxford Handbook of the History of Analytic Philosophy, edited by Michael Beaney. It focuses on the psychological origins of analytic philosophy. Analytic psychology influenced the emergence of a new method in philosophy and the crucial changes to the notions of judgement and intentionality at the end of the nineteenth century. In particular, G. F. Stout’s analytic psychology played an important role in the formation of Moore’s and Russell’s early analytic philosophy. Through Stout, the account of judgement and intentionality given by Brentano and Twardowski also had a significant influence on the development of early analytic philosophy.