In this chapter, I focus on three different topics to illustrate the complicated and often surprising ways in which Aristotle’s investigations of animals and of the heavens are related to one another. After an introductory discussion of how Aristotle differentiates these different scientific investigations of nature from one another, this chapter looks at (1) the dependence of Aristotle’s account of cosmic directionality (in De caelo II.4) on his discussion of directional concepts in his account of animal locomotion (De incessu animalium 1-6); (2) the relationship between his account of gestation periods in De generatione animalium IV.10 and his understanding of the complex relationship between the solar and lunar cycles; and (3) his teleological explanation of why there are distinct male and female contributors to animal generation (and why animals generate at all) at the beginning of De generatione animalium II as it relates to his discussion of the cyclical nature of all generation that closes Generatione et Corruptione II.11.