<p>This is a paper about model-building and overfitting in normative ethics. Overfitting is recognized as a methodological error in modeling in the philosophy of science and scientific practice, but this concern has not been brought to bear on the practice of normative ethics. I first argue that moral inquiry shares similarities with scientific inquiry in that both may productively rely on model-building, and, as such, overfitting worries should apply to both fields. I then offer a diagnosis of the problems of overfitting in moral inquiry and explain how our current practice seems worryingly susceptible to such problems. I conclude by giving suggestions for how we might avoid overfitting when doing normative ethics.</p>