Rauscher works mainly in the philosophy of Immanuel Kant. The central concern of his recent book Naturalism and Realism in Kant’s Ethics (Cambridge, 2015) is Kant's metaethics and its relation to naturalism, realism, and cognitivism. He has also published work on Kant's ethics, political philosophy, metaphysics, philosophy of history, and methodology. Additional research areas cover British Empiricists and German Idealists historically; and the relation between evolution and ethics in contemporary philosophy. Rauscher has edited and translated Kant's unpublished notes, essay drafts, and course lectures for Kant, Lectures and Drafts on Political Philosophy (2016), and translated similar notes on ethics as a contributor to Kant, Notes and Fragments (2005), both in the Cambridge edition of the Works of Immanuel Kant. In 2012 he was a Fulbright Scholar at the Federal University of Santa Catarina, Brazil.