In this study, we explored how elementary school students used multiple information resources in responding to a text-based argumentation task asking them to research a set of online texts in order to state and justify their stance on a controversial health-related issue. Results showed that most students took a stance that was consistent with the majority of the information resources that they read, that they mainly drew on more reliable resources in their written task products, and that they justified their stance by providing one or more supporting reasons. Students relied much more on copying and paraphrasing content from the online resources than on integrating information within and across the resources, however, and they very rarely referred to the sources in their written products. In general, girls were found to outperform boys on measures of content, argumentation, and integration in the written task products, and these aspects of the written products were also positively related to students’ basic reading and reasoning skills. The discussion highlights the challenges many elementary school students experience in this complex literacy task context, suggests some avenues for future research, and discusses instructional implications of the study.