Developing and applying epistemic ideals or criteria is a corecomponent of epistemic practices.In history education,epistemic criteriahave been included in approaches to teaching history as well as in theoretical frameworks for investigating the learning and understanding of the domain. One justification for these frameworks is in the epistemic practices of expert historians; however, empirical evidence abouthistorians’ epistemic criteriais scarce. Thus, we set out toexplore epistemic criteria historians use to determinequality in their own and others’ workthroughan analysis ofinterviewswith 26 Finnish historians. We identified over 80 criteriathatwe placedin categories such as internal characteristicsof works; connections to past and present knowledgeand practices;connections to future knowledge and practices;proxies; connections to non-epistemic use; and emotions. These findings openup possibilities for better developing criteria in history education and considering their connections to those of experts.