In the reading of Heidegger presented in Aporias, Derrida thematizes a number of issues that are central to his work, early and late: temporality (waiting), undecidability (the im-possible), and humanism (animality). Here, we examine the oddly neglected Heideggerian context of these Derridian questions in Sein und Zeit. We propose to examine the textual articulation of Derrida’s argument, attempting to draw attention to neglected aspects and unseen consequences in that reading. We will ask how these consequences, in the final analysis, complicate Derrida’s larger argument. Our aim is not to subvert the latter, but rather to unfold the tensions that it contains and the difficulties that it quietly negotiates.