This essay analyzes Derrida's questioning of the relationship between "Theory and Practice" in his recently published seminar of 1976-1977 of this same title. It traces Derrida's reading of this relationship in Marx and Marxism, beginning with various interpretations (such as Althusser's) of the famous line from Marx's "Theses on Feuerbach," "Philosophers have only "interpreted" the world, in various ways; what is important is to transform it." The essay tries to argue that Derrida's reading of theory and practice in Marx should be used in the end to reread Derrida himself and so rethink the relationship between theory and practice in deconstruction and, especially, in "pedagogy." After tracking the places where Derrida's seminar, first presented in Paris to help prepare students for the 1977 "agrégation" exam in philosophy on the theme of "Theory and Practice," repeated, overlapped with, or anticipated many prior and subsequent treatments of similar themes in Derrida's published works, the essay concludes that no seminar--and Derrida's seminars are exemplary in this regard--can be restricted to the time in which they are given but are always, like Derrida's "specters of Marx," non-contemporaneous with themselves, in a word, "out of joint."