Despite enormous growth in the study of learners' cognitive processes, relatively little is known about how learners reason about social phenomena and issues involved in disciplines, such as history. Yet, according to scholars the process could hardly be more important, and it demands redress and scientific explanation. To contribute to the understanding of learners' reasoning about historical issues, an empirical research project, on the cognitive processes of learners' while explaining the causes of an historical event, was undertaken. The data obtained showed that difference in age and expertise tended to lead to different types of historical explanation. A model to induce learners' understanding of an historical event is put forward.