en Development and Validation of a Model for Predicting Productivity Based on Psychosocial Factors in Administrative Staff; The Mediating Role of Physical and Mental Health Aims: This study aimed to develop and validate a model for predicting productivity in university administrative staff. Instrument & Methods: In this cross-sectional study, 614 participants completed a survey that included the Job Stress Questionnaire, Job Security Scale, Role Clarity Scale, Distributive Justice Subscale, Procedural Justice Subscale, Job Content Subscale, Physical Health Questionnaire, Depression, Anxiety, and Stress Scale, and Stanford Presenteeism Scale. To validate the proposed model, structural equation modeling was conducted using SPSS 23 and AMOS 23 software. Findings: Distributive justice, job content, and procedural justice had the greatest direct impact on employee productivity. Additionally, workload, colleague support, management support, role clarity, and procedural justice were found to have significant positive relationships with mental health. Workload, management support, and job content also showed significant positive relationships with physical health, and both mental health and physical health positively predicted presenteeism. The findings revealed a mediating pathway in the relationship between mental health, physical health, and productivity. The data further suggested that mental health has a substantial impact on physical health. Moreover, mental health was found to mediate the relationship between job stressors and presenteeism through its effect on physical health. Conclusion: Psychosocial factors, including distributive justice, job content, and procedural justice, have the greatest impact on employee productivity. Mental Health,Workload,Presenteeism,Work Performance, 291 298 http://daneshafarand.org/browse.php?a_code=A-10-60731-3&slc_lang=en&sid=4