Charles Peirce claimed that the principal ingredient in assertion is an act of “taking responsibility” for the truth of what is asserted. Some people writing about the Commitment Theory of Assertion have at times construed Peirce’s claim as his espousal of that contemporary theory, but this, I argue, is mistaken. Peirce saw “taking responsibility” as the assumption, not of an obligation, but instead of a liability, a penalty to be incurred if one’s assertion turned out to be false. I then consider how this point connects to other parts of Pierce’s analysis of assertion, specifically his claims that we assert to persuade, that assertion involves an intentional exhibition of our assumption of liability, and that this assumption of liability furnishes evidence for what is asserted. I conclude by sketching on Peirce’s behalf how the assumption of liability could constitute, and be intelligibly offered as, evidence for what is asserted.