Self-reflection is considered a central component in the training of clinical psychologists and requires accurate self-assessment of psychotherapeutic competencies. However, previous research suggests that self-assessment of psychotherapeutic skills is prone to biases. The aim of this study was to assess the ability of master's students to evaluate their own competencies and to identify person-specific and situational factors predicting self-assessment.The study was conducted as part of the communication skills practicum in the master's program in Clinical Psychology and Psychotherapy at the University of Mannheim. At the end of the practicum, students conducted an anamnesis interview with simulated patients. Subsequently, 39 master's students assessed their own psychotherapeutic competencies in the anamnesis interview using the Cognitive Therapy Scale. Additionally, a trained expert evaluated the competencies to compare self-assessments with external evaluations. Therapeutic self-efficacy was recorded before the practicum as a person-specific factor predicting self-assessment. The difficulty of the simulated interview was coded to determine situational factors.On average, the agreement between self-assessment and external evaluation of competencies was low (ICC=0.25). Overall, students underestimated their psychotherapeutic competencies, particularly when their performance was above average. However, when their performance was below average, they tended to overestimate their competencies. Especially higher therapeutic self-efficacy predicted more positive self-assessment scores. Higher self-efficacy was also associated with an overestimation of one's own competencies.The results of the study indicate that self-assessment of psychotherapeutic competencies by master's students is subject to systematic biases. Initial findings also suggest that person-specific factors are better predictors of the distortion of self-assessment than situational factors.To ensure beneficial self-reflection, master's students should be trained in the reliable assessment of their own psychotherapeutic competencies.