Online collaborative argumentations need instructional support to ensure social interactions and in-depth cognitive engagement. It is known that graphic organizers assist in comprehending information and negotiating meanings for individual and collective tasks. This study intends to compare the effects of different graphic organizers in asynchronous online discussions. Specifically, it investigates three graphic organizers collaboratively constructed by learners, including t-charts, tree charts, and maps. A t-chart is a table that shows two sides of a subject (e.g., pros vs. cons). A tree chart gets a subject to branch out into multiple subtopics, displaying a hierarchy of topics. A map depicts relations of a topic with nodes and links. This study examines the three graphic organizers' impacts on social, cognitive, and affective engagements in online collaborative argumentation. A quasi-experimental study was conducted in an online graduate course where 36 students participated in case-based discussions with a graphic organizer for each group. The results demonstrated that more alternative ideas were generated in t-charts than the other types, which shows varying levels of knowledge construction. In terms of participatory and attitudinal aspects, we did not find a significant difference across the types of graphic organizers. This study suggests the form of a graphic organizer affects how learners construct knowledge in collective work. Affordances of each type of graphic organizer and their applications in online instructional settings were discussed.