In this essay I describe how contractarianism might approach interspecies welfare conflicts. I start by discussing a contractarian account of the moral status of nonhuman animals. I argue that contractors can agree to norms that would acknowledge the “moral standing” of some animals. I then discuss how the norms emerging from contractarian agreement might constrain any comparison of welfare between humans and animals. Contractarian agreement is likely to express some partiality to humans in a way that discounts the welfare of (...) some or all animals. While the norms emerging from the contract might be silent or inconsistent in some tragic or catastrophic cases, in most ordinary conflicts of welfare, contractors will agree to norms that produce some determinate resolution. What the agreement says can evolve depending upon how the contractors or the circumstances change. I close with some remarks on contractarian indeterminacy. (shrink)