Background and Purpose: Background and Objective: Academic achievement is an important concern for families and education system experts, and because future success depends on students' academic performance and progress, researchers have been looking for solutions to increase it. Academic failure or lack of academic success causes negative emotions such as anxiety, anger, and depression in students and families. With the repetition and continuation of these failures and emotions, their self-confidence decreases, and it also causes learned helplessness and other disorders, all of which will lead to psychological and social consequences that are very difficult and costly for families and educational institutions to compensate. Therefore, paying attention to this segment of society in terms of education and upbringing will lead to greater productivity and prosperity of the education system. Therefore, the present study was conducted with the aim of determining the effectiveness of positive thinking training on academic flourishing and learning self-efficacy of first-year high school students.
 Methods: The method of this study was a semi-structured pre-test-post-test design with a control group. The statistical population consisted of all female first-year high school students in District 18 of Tehran in 2024. Among them, 40 eligible volunteers were selected using a multi-stage cluster random sampling method and randomly assigned to the intervention and control groups (20 people in each group). Due to the high willingness of the participants to change and be active in the group, none of the groups dropped out. In the pre-test-post-test, the two groups completed the 18-question Academic Flourishing (Schreiner et al., 2009) and 30-question Academic Self-Efficacy (Jink and Morgan, 1999) questionnaires. Positive thinking training based on Quilliam's (2003) package was implemented on the intervention group in eight sixty-minute sessions, each session once a week; but the control group did not receive the treatment program. Data analysis was performed using analysis of covariance in SPSS version 27 software. The significance level of the tests was considered to be 0.05.
Results: The results of the study indicated that positive thinking training was effective in increasing academic flourishing and learning self-efficacy dimensions of junior high school students in the experimental group (P<0.001); also, the treatment effect size for academic flourishing variables and learning self-efficacy dimensions (talent, context, and effort) was 0.32, 0.41, 0.63, and 0.001, respectively.
Conclusion: Positive thinking interventions include therapeutic methods or activities that aim to promote positive emotions, positive behaviors, positive cognition and perception, and enhance well-being in individuals. This specific field of psychology focuses on human success. Positive thinking training helps reduce anxiety caused by negative thoughts, cognitive-behavioral self-regulation, control and management of negative emotions, and as a result, improve academic performance, increase positive beliefs, increase thinking power, and ultimately learning self-efficacy. From the results obtained, it can be inferred that training positive thinking skills probably has encouraging effects and can broaden action and thinking in education, leading to avoidance of despair and increased vitality. Academic flourishing and learning self-efficacy lead to the flourishing of talents, and a cheerful, dynamic, and active person in academic life strives hard for his goals, and therefore reduces the level of depression. Positive thinking skills, as a psychological approach, have a profound impact on students' behavior and social interactions. These skills help individuals focus on solutions and opportunities rather than problems. This change in attitude increases students' self-confidence and encourages them to be more active in social situations. When students are positive, they usually feel more optimistic about themselves and others. This feeling of optimism helps them achieve academic flourishing and learning self-efficacy. Accordingly, teachers are suggested to create positive beliefs in students and develop a positive, active, and cheerful school environment to provide the conditions for the growth of students' academic flourishing and learning self-efficacy.