This thesis examines the effects of the UGL course (Development of Group and Leader), a popular leadership training program in Sweden. The study analyzes differences in leadership styles, particularly transformational and destructive leadership, between leaders who have completed the UGL course and those who have not. Using a quantitative method, participants self-evaluate their leadership behaviors with the Developmental Leadership Questionnaire (DLQ). The results indicate that UGL participants report an increase in transformational leadership and a decrease in destructive leadership, although these changes were not statistically significant. The study highlights how self-awareness, a major component of UGL, can influence leadership quality. It also points to the need for further research with larger and more diverse sample groups to validate the results and establish statistical significance.