Abstract: This study investigated the effect of graphic organizer and instructional scaffolding on argumentative essay writing performance among TESL undergraduates. The study employed an experimental research using the pre-test and post-test design involving 60 TESL undergraduates who underwent lessons on argumentative essay writing using two different delivery modes, namely ‘Graphic Organizer with Instructional Scaffolding’ (GOIS) which is the experimental group and ‘No Graphic Organizer No Instructional Scaffolding’ (NGNI) which is the control group.