en Statistics and epidemiology پژوهشي Research <div style="text-align: justify;">This was a quasi-experimental study with a pretest-posttest design, a control group and follow-up. The study population included all high school students in the city of Torbat-e Jam (Iran) in 2016. The subjects were selected via availability sampling and then randomly assigned into two groups of 20 (an experimental and a control group). The subjects in the experimental group participated in 60-minute weekly self-efficacy group training sessions for seven weeks. No intervention was done for the control subjects. After the training sessions, the achievement motivation and self-efficacy scales were used to collect posttest data. The collected data were analyzed with SPSS (version 16) using descriptive statistics, analysis of covariance, the Levene&rsquo;s test, regression analysis and the Bonferroni post-hoc test. All statistical analyses were performed at significance of 0.05. <strong>Results:</strong> After the training period, the mean self-efficacy score increased from 13.76 &plusmn; 3.02 to 14.34 &plusmn; 3.47 and the achievement motivation score increased from 12.58 &plusmn; 6 to 14.37 &plusmn; 4.1. There were statistically significant differences in terms of pretest and posttest scores between the two groups. Results after two months of follow-up also indicated that the intervention results persisted in the experimental group. <strong>Conclusions: </strong>Considering the positive impact of the self-efficacy group training on self-efficacy and achievement motivation, it can be suggested as an effective cognitive intervention in educational counseling.</div> Self-efficacy training, achievement motivation, self-efficacy, high school students 32 38 http://jcbr.goums.ac.ir/browse.php?a_code=A-10-76-10&slc_lang=en&sid=1 Zahra Shokhmgar زهرا شخمگر 10031947532846001359 10031947532846001359 Yes Faculty of Psychology, Payame Noor University, Torbat-e Jam, Iran پیام نور تربت جام Malihe Mohammad pour ملیحه محمدپور 10031947532846001360 10031947532846001360 No Faculty of Psychology, Payame Noor University, Torbat-e Jam, Iran پیام نور تربت جام Mohammad Sanjari محمد سنجری 10031947532846001361 10031947532846001361 No Faculty of Psychology, Payame Noor University, Torbat-e Jam, Iran پیام نور تربت جام