Abstarct: Abstract Human resources efficiency is the maximum appropriate use of human resources in order to achieve the goals of the organization with the least time and minimum cost. On the other hand, one of the general functions of organizations is the socialization of new employees. The major aim of organizational sociability is to transfer information related to the job and task to the new person of the organization. Accordingly, the purpose of this study was to investigate the effect of organizational socialization on the productivity of sports volunteers with a mediating role of citizenship behavior. The descxriptive and correlational research method was used in this study. The statistical population of this study was active people in sports delegations of Sistan and Baluchestan provinces in 2020. Sample size calculations were performed using G*Power. Finally, one hundred and fifty-nine people were analyzed. The Persian version of the organizational sociability questionnaires baxsed on the Taormina model (1998), Hershey and Goldsmith productivity questionnaire (1994) and Jung and Jung (2015) citizenship behavior questionnaire was used. Structural equations with a variance-baxsed approach was applied to statistically analyze the data. Data were analyzed using SPSS and SMART-PLS software. The results showed that organizational socialization has a positive and significant effect and on productivity and citizenship behavior. Also, citizenship behavior has a positive and significant effect on productivity. Citizenship behavior has a mediating role in the relationship between socialization and organizational productivity. Therefore, it is suggested to the managers and officials of the sports and youth departments and the sports delegations that work in this field that volunteer management courses be considered for the heads of the sports delegations..