This article investigated the impacts of mind mapping on the vocabulary development of fifth-graders at Tran Quoc Toan Primary School. The present study utilized a quasi-experimental design: pretest, posttest control group design. Participants were 68 students divided into two groups: the experimental group (Class 5/4) and the control group (Class 5/2). The experimental group was taught mind mapping techniques while the control group received conventional methods. Before the intervention, a pretest was administered to both groups to ensure that their vocabulary level is similar. Subsequently, an 18-week treatment was implemented. A posttest was conducted after the intervention to examine students’ vocabulary. The results of the posttest analysis indicate students in the experimental group improved their vocabulary performance was significantly higher than the ones in the control group. In addition, the data obtained from the questionnaire and interviewsof the experimental group revealed that the participants expressed a positive attitude toward using mind mapping techniques.