In this chapter, I introduce readers to the problem of wild animal suffering (WAS) and explain why it’s so pressing. I note that many wild animal species, specifically r-strategists, protect their genes by producing large numbers of uncared-for offspring, most of whom die painfully and prematurely. As a result of the r-strategy, the vast majority of sentient animals born into the world live terrible lives, making the scale of WAS truly massive. In addition, WAS has so far been neglected by most scholars and advocates and thus, two of the selection criteria used by effective altruists (scale and neglectedness) strongly favor making WAS a priority cause. I finish this chapter by outlining the arguments I make in subsequent chapters.