Scott Sturgeon has recently challenged Pollock’s account of undercutting defeaters. The challenge involves three primary contentions: (1) the account is both too strong and too weak, (2) undercutting defeaters exercise their power to defeat only in conjunction with higher-order beliefs about the basis of the lower-order beliefs whose justification they target, and (3) since rebutting defeaters exercise their power to defeat in isolation, rebutting and undercutting defeaters work in fundamentally different ways. My goal is to reject each of these contentions. I maintain that (1) Sturgeon fails to show that Pollock’s account of undercutting defeaters is either too strong or too weak, (2) his own account of how undercutting defeaters exercise their power to defeat is both too strong and too weak, and (3) his claim that rebutting and undercutting defeaters work in fundamentally different ways is mistaken.