The authors examined whether the influence of reading purpose on reported use of text-processing strategies was moderated by students' prior knowledge about the topic of the text. Using multiple regression analyses with interaction terms, they found that the effect of reading purpose on reported use of memorization and elaboration strategies depended on students' level of topic knowledge. For participants who read for the purpose of discussing text content, reported use of memorization and elaboration was positively related to topic knowledge, whereas no relation between reported use of such strategies and topic knowledge was found for participants who read for the purposes of test taking or summary writing. This suggests that students' flexible use of text-processing strategies may depend on their topic knowledge.