This dissertation examines the problem of teleology in early modern German philosophy. The problem, briefly, is to account for the proper sources and conditions of the use of teleological concepts such as design, purpose, function, or end in explaining nature. In its modern guise, the status of these concepts becomes problematic with the rise of modern science in the seventeenth century, which reconceived the physical world as fundamentally inert and purposeless and rejected the medieval view of the world as governed by goal-directed powers. This disssertation argues that the reception of the new science in Germany was deeply conditioned by the metaphysics of late-medieval scholasticism. It situates the better known thinkers of the German Enlightenment, such as Gottfried Leibniz, Christian Wolff, and Immanuel Kant, in relation to the later medieval tradition, originating with sixteenth- and seventeenth-century authors such as Francisco Suárez, Christoph Scheibler, and Johann Clauberg. I show that Leibniz, Wolff, and Kant inherit from neo-scholasticism two classical assumptions bearing on teleology: first, a version of the classical thesis of the equation of being and the good (ens et bonum convertuntur), or that every being manifests goodness or desirability in some measure; and second, a tight conceptual dependence of final causation on rational cognition such that any appeal to purposes or ends in explanation entails an appeal to rationality. Leibniz’s, Wolff’s, and Kant’s acceptance of these positions underlies their shared commitment to view not only goal-directed animal behavior but also any contingent unity of laws (such as the unification of Newtonian laws of motion through the law of universal gravitation) as presupposing a rational connection. Teleological unity, or a unity of purpose, appears in this tradition as an evident natural fact in need of explanation at the cosmological, biological, and psychological levels. At the same time, Kant departs from his predecessors in crucial respects. For Kant, the conditions for legitimately judging nature as if it were purposively constructed are borrowed not from a divine guarantee of order but from the essence of human reason itself, when, in his terms, reason is properly described as a goal-directed natural power. The problem of teleology, with Kant, becomes reconfigured as essentially concerned with the ends of human reason.