Objective: This study aimed to compare the effectiveness of Transference-focused Psychotherapy (TFP) and Acceptance and Commitment Therapy (ACT) on promoting the mental health and psychological capital of staff working in hospitals covered by social security in Tehran Province. 
Methods: The present study was a quasi-experimental research with pre-test and post-test. The statistical population of the present study was the personnel working in hospitals covered by social security in Tehran Province. A total of 120 personnel from three hospitals were randomly divided into two experimental groups and one control group (40 people in each group). All three groups answered the Mental Health Questionnaire (Symptom Checklist-90-R (SCL-90-R)) and Psychological Capital Questionnaire (PCQ) as a pre-test. Then, the transfer-oriented treatment group and the acceptance and commitment treatment group (during eight sessions) received the experimental intervention and the control group did not receive any kind of intervention. At the end of the sessions, all three groups answered the questions of the SCL-90-R and PCQ again. Multivariate analysis of covariance was used to analyze the collected data. 
Results: The results of the present study showed that both TFP and ACT were effective in promoting the mental health of staff working in hospitals covered by social security. There was also a difference between the effectiveness of TFP and ACT in promoting the mental health of staff working in hospitals covered by social security. Thus, in the TFP group, the components of anxiety, morbid fear, psychosis, and paranoia gained significantly lower scores compared to the ACT group. Regarding the components of psychological capital, the ACT group scored significantly lower than the TFP group.
Conclusion: Both methods can be used by counselors and therapists to promote the mental health of staff working in hospitals covered by social security.