An important goal of history education is the development of a chronological frame of reference that can be used to interpret and date historical images and documents. Despite the importance of this contextualization goal, little is known about the knowledge and strategies that allow students to situate information historically. Two studies were conducted to uncover the contextualization process. The first exploratory process investigation involved 18 students working in dyads to interpret and date two cartoons and a historical text. Subsequently, we conducted an experimental study with 114 students to investigate the effects of a knowledge training and strategic support. Outcomes support the idea that a rich associative network of historical knowledge organized around key historical concepts and knowledge of landmarks helps students anchor and calibrate timelines for effective contextualization. Results also suggest that systematic consideration of potential clues will not contribute additional contextualization power prior to internalization of relevant knowledge. (Contains 7 tables.)