<p>The present study presents a structural model of clients' mental health and their motivation to participate in prison vocational training courses. The research population included all male and female clients in Arak Prison, located in Markazi Province, Iran. Among them, 83 individuals were selected as the research sample using a stratified sampling technique with proportional assignment. The data collection instruments were the Goldberg General Health Standard Questionnaire and the Harter Academic Motivation Questionnaire. The validity of these instruments was confirmed by a panel of experts, and their reliability was assessed using Cronbach’s alpha coefficient and the composite reliability index. Data were analyzed using the partial least squares statistical method in SmartPLS software. Based on the total mental health score (sum of the four subscales: physical health, anxiety, social action, and depression), 41% of clients were found to be at risk. Moreover, more than 60% of the clients demonstrated an average level of educational motivation. Physical health, depression, anxiety and sleep disorders, and social action explained 44.2% of the variance in clients' educational motivation to participate in vocational training courses, with physical health, anxiety and sleep disorders, social action, and depression contributing the most, respectively. In addition, the three constructs of physical health, depression, and anxiety and sleep disorders accounted for a total of 64.6% of the variance in clients’ social action.</p>