Dialogic approaches to education have become the new predominant paradigm in socio-cultural perspectives on learning (e.g., Alexander, 2020). Yet little research has addressed emotion regulation of educational dialogues in relation to cognitive progress. The practice of Community of Philosophical Inquiry (CPI) with children offers a golden opportunity to investigate this literature gap. CPI aims at fostering reasoning thanks to kairos, these opportune, disruptive contributions that, when appropriately taken up, improve problem understanding. Such a process relies on astonishment, an inseparably cognitive-affective way to welcome and elaborate kairos (Thiévenaz, 2016). We focus on the affective dimension of taking advantage of kairos opportunities. On the basis of 8 video-taped CPI sessions in diverse contexts, involving French primary and secondary school students, and recorded in 2015–2018, we identify when kairos arises and compare the ways in which participants react emotionally to kairos. We also illustrate the educational outcomes provoked by specific reactions. Using qualitative and multimodal linguistic analysis (Mondada, 2016), we empirically define 6 typical scenarios of kairos emotion regulation, specify the resources that they require, the goals that they allow to achieve, and how they echo the strategies of the model of emotion regulation in achievement situations (Harley et al., 2019). A deep analysis of a short excerpt of dialogue illustrates how the emotional emphasis of kairos sets the ground for its further exploitation for collective reasoning. Our work offers a better understanding of the role of emotions in educational dialogues and points out the interactional nature of emotion regulation.