Several studies have explored the effects of cognitive tools, such as scaffolding, on the quality of argumentation in online argumentation activities. However, although information searching is the most popular online activity, few studies have investigated the roles of online information resources in the quality of argumentation. This study explored the role of information searching strategies in the quality of argumentative essay writing. Participants were 91 eighth-grade students from two classes at a junior high school in southern Taiwan. Results showed that students' online argumentation and information searching behaviours were clustered into three strategies, namely "browsing for discussion," "browsing without discussion," and "less information seeking." The results also demonstrated that students who adopted the "browsing without discussion" strategy had higher quality argumentation skills in claims, grounds, warrants, and rebuttals than those students who used the "less information seeking" strategy. Students who used the "browsing for discussion" strategy had higher quality argumentation skills in rebuttal than those students with the "less information seeking" strategy. Hence, this study highlights the positive role of students' information searching strategies for explaining the quality of argumentative essay writing.