The purpose of the present study is to investigate the effectiveness of a training programme on constructive thinking skills in reducing the psychological defeatism level and attitude towards intellectual extremism among university students and to examine the continuity of its effectiveness after the follow-up period. A quasi-experimental research design with one training and one control group and three measurements (pre, post and follow-up) was used. Twenty students participated in the research with 12 in the experimental group and 8 in the control group. The training programme on constructive thinking skills was applied to the experimental group over a period of 16 sessions. No application was conducted on the control group. The psychological defeatism scale, the attitude towards intellectual extremism scale and the constructive thinking scale were applied to the participants. Data were analysed by Mann-Whitney and Wilcoxon tests. The findings of this research indicated that the training programme on constructive thinking skills has caused a significant decrease in the experimental group's psychological defeatism and attitude towards intellectual extremism levels. Besides, there were no significant differences between the mean scores of the experimental group in the post and follow-up measurements of the psychological defeatism and the attitude towards intellectual extremism a month later. Research findings were discussed within the context of the related literature and some suggestions were provided for researchers and stakeholders.