This research aimed at investigating the effectiveness of Toulmin’s model of argumentation within TWPS strategy on undergraduate students’ critical thinking on argumentative essay. A quasiexperimental design with a pretest-posttest and nonrandomized control group design was used. The subjects were 38 fourth semester students in English Department of Universitas Negeri Malang. The experimental group was treated by using Toulmin’s model of argumentation within TWPS strategy while the control group was treated without TWPS strategy. Students’ critical thinking ability was measured by using argumentative essay test. ANCOVA was used to test the hypotheses. Findings showed there was not significant difference on the students’ critical thinking ability. However, Toulmin’s model of argumentation within TWPS strategy proved to improve the students’ critical thinking as shown by the improvement of the experimental group’s mean score.