This article reports on a review of research into students' reasoning about social change and causes they attribute to selected historical events. In this review, I distinguish studies into social change and causality as two methodological approaches to historical understanding before relating findings into the ways that students reason about agency in social change. I consider two of many possible explanations for these findings, one each from a cognitive and a social psychology perspective. I then turn to sociology for two articulations of agency as tools to enhance students' historical thinking and reflection on their variegated capacities as agents of social life: a) personal agency as nested moments of re-"iteration," "practical evaluation," and "projectivity" and b) historical agency as collectively expressed struggle over the ideals, images, and stories people use to reiterate a past in the present so as to imagine personal and social projects. I argue throughout that student attention in classrooms to assumptions about agents and agency used in historical explanations enhances both their historical explanations and capacities as citizens. Rather than citizens, however, I begin this article with a feminist argument that teachers address students first and foremost as agents. (Contains 3 notes.)