This study examined the effects of external strategy use on the comprehension of relations among controversial texts. About 80 undergraduates read six controversial texts for the purpose of either finding intertextual relations or forming their opinion about the controversial issue. Half of them were permitted to use external strategies, the other half were not. Results indicated that only when given a purpose of relation-finding did external strategy users perform better than non-users in the comprehension of intertextual relations. Readers with a purpose of relation-finding also outperformed readers with a purpose of opinion-forming when permitted to use external strategies. The use of external strategies had no influence on the recall of intratextual arguments, regardless of reading purpose. These results were discussed in terms of readers' use of external strategies to serve their reading purposes.