What role does ideational change play in norm emergence? While there has been some attention to changes in the application of norms, most scholars refer to the ideas that are associated with a norm’s practice as being fixed. I argue that ideational change is a causal mechanism that facilitates norm emergence. In particular, I propose three types of content change that capture changes in the ideas associated with the goals expected to be attained by the application of the norm (‘logic of consequences’), with its morality (‘logic of appropriateness’), and with its relations with similar or alternative practices (‘specification’). These changes in the rational and moral reasoning and argumentation that frame the practice that is associated with an emerging norm are likely to make this practice congruent with more contexts and appealing for more states. To illustrate the content change proposition, this article traces the emergence of the international norm of truth and reconciliation commissions. In the debates that followed the South African Truth and Reconciliation Commission, truth and reconciliation commissions shifted from being seen as a political compromise to being regarded as a ‘holistic’ tool for social and political reconstruction and came to be associated with multiple democratizing effects. Truth and reconciliation commissions also shifted from being the ‘weaker alternative’ to trials to a practice that is morally equal and complementary to the judicial option. Taken as a whole, these changes in the expected utility, morality, and specification of truth and reconciliation commissions facilitated their emergence and consequent institutionalization as an international norm.