Applying active learning to promote students' critical thinking disposition is one of a current educational goal. However, it is very rare to find the research that explores the critical thinking disposition, particularly for the students who are prospective elementary school science teachers. This study aims to investigate the effects of collaborative inquiry learning on the critical thinking disposition. A quasi-experimental design with a pre-test/post-test control group was used. The total of 149 students of primary school teacher education programs participated in this study. They were divided into two groups, namely the experimental group who received treatment with the collaborative inquiry learning strategy (experiment) and the control group received treatment with the conventional strategy. The critical thinking disposition data were obtained through the critical thinking disposition inventory test and analyzed by using paired t test. The findings of this study indicate that the students in the experimental class who were exposed to collaborative inquiry learning obtained higher critical thinking disposition scores than the students in the control class. The findings of this study reveal that collaborative inquiry learning can be an effective strategy to improve critical thinking disposition.