This study presents a theory-informed cognition model of causal reasoning in history as a foundation for assessment tasks. This model details the levels of achievement of individuals’ causal reasoning in history and the underlying beliefs and knowledge types that should be mastered to become proficient in this form of reasoning. The model was developed following a design approach. First, a literature study was conducted on the nature of causation in history. This study led to the creation of an initial model that was submitted to two mixed expert panels comprising experts from various backgrounds who critiqued the model. Based on their feedback, the model was further refined. This process resulted in a description of levels of achievement for three dimensions: an epistemic dimension, a second-order knowledge dimension and a first-order knowledge dimension. For each dimension, we identified concrete behaviour and underlying knowledge and beliefs. This cognition model can form the foundation for developing assessment tasks that can help improve students’ causal reasoning in history.