Assessment materials must be checked for errors before they are presented to candidates. Any errors have the potential to reduce validity. For example, in the most extreme cases, an error may turn an otherwise well-designed exam question into one that is impossible to answer. In Cambridge University Press & Assessment, assessment materials are checked by multiple assessment specialists across different stages during assessment development. While human checkers are critical to this process, we must acknowledge that there is ample research showing the shortcomings of being human (e.g., we have cognitive biases, and memory and attentional limitations). It is important to provide assessment checkers with tools that help overcome or mitigate these limitations. This article is about one type of checking tool -- checklists. We describe a research-informed, collaborative project to support assessors in performing their checks of exam papers. This project focused on redesigning the instructional, training and task materials provided to assessors. A key part of this was to design checklists for assessors to use when performing their checks. In this article, we focus primarily on the approach that we took for these checklists in order to draw readers' attention to the complexity that is involved in designing them and to provide a practical example of how research can be used strategically to inform key design decisions.