This paper guides the reader through the use of functions in contemporary legal philosophy: in developing those philosophies and through methodological debates over their proper role. This paper is broken into two sections. In the first I canvass the role of functions in the legal philosophies of several mid to late twentieth century Anglo-American general jurisprudents whose theories are still common topics of discussion: Ronald Dworkin, H.L.A. Hart, Lon L. Fuller, John Finnis, and Joseph Raz. In the second, I examine contemporary arguments over the role of functions in the methodology of legal philosophy.