Atheists argue that animal pain, disease, suffering, and death cause a problem for theism because they believe that an all-knowing, all-powerful, and all-good God would not use millions of years of animal suffering just to make a world suitable for humans. Animal suffering was not a concern for theism through the medieval period, but it has been increasingly discussed in philosophy of religion since modern times, and there is especially a large and growing amount of literature on this subject that has been published in the last few decades. This handbook serves as a guide for those interested in the literature on the problem by bringing together experts in the philosophy of religion, theology, environmental ethics, and the philosophy of animal minds. It not only presents major formulations of the problem of animal suffering and major theodicies, but it also discusses metaethical issues regarding animal suffering, the question of animal consciousness and self-awareness and their implications for animal suffering, and what implications available theodicies might have for animal ethics.