This paper seeks to widen the dialogue between the “epistemology of peer disagreement” and the epistemology informed by Wittgenstein’s last notebooks, later edited as On Certainty. The paper defends the following theses: (i) not all certainties are groundless; many of them are beliefs; and they do not have a common essence. (ii) An epistemic peer need not share all of my certainties. (iii) Which response (steadfast, conciliationist etc.) to a disagreement over a certainty is called for, depends on the type of certainty in question. Sometimes a form of relativism is the right response. (iv) Reasonable, mutually recognized peer disagreement over a certainty is possible.—The paper thus addresses both interpretative and systematic issues. It uses Wittgenstein as a resource for thinking about peer disagreement over certainties.