From the context of Early Modern Philosophy and the Scientia Nova of Seventeenth-century, this article has the aim to review the philosophical proposal of Pierre Gassendi (1592-1655) about his concept of matter, causality, and the teleological character of his Philosophy of Nature. In order to interpret with accuracy the philosophical ideas of Gassendi, we have to take the teleological issues into account. In order to understand Gassendi's approach we offer, on first place, a theoretical framework introducing his intellectual activity; second, we study the atomistic and creationist principles of his materialism and his interpretative problems; third, we examine the probabilistic version of his philosophy; fourth, we expose the gassendian discussion about the Aristotelian principles of causality and his recovery of the final cause on the context of his theory of generation. Finally, we offer our interpretation of Gassendi's ideas, trying to convey the basic conceptual elements required to understand the philosophical tensions expressed in his natural "teleo-mechanicism".