Objective: The main purpose of this research was study the role of citizenship participation, meritocracy and organizational structure (bureaucratic and traditional) in the organizational citizenship behavior, affiliation organizational commitment and trust to coworkers. Method: From A group organizations (bureaucratic) one thousand and two hundred twenty two and from B group organizations (traditional) four hundred seventy seven (from throughout of Iran) were selected with the use of multi stage sampling method. Five questionnaire used in this research: meritocracy, citizenship participation, organizational citizenship behavior, affiliation organizational commitment, and trust to coworkers. Findings: the analysis of variances showed that meritocracy, citizenship participation and organizational citizenship behavior were significantly higher in A group (bureaucratic) organizations than B group (traditional) organizations. Afterward, organizational structure in the form of artifact variable entered to hierarchical regression analysis. The result showed that meritocracy in A group organizations significantly increased the organizational citizenship behavior. The same result also showed that in A group organizations, citizenship behavior adjusts the effect of meritocracy on citizenship participation. But in B group organizations, after control of meritocracy, it has significant relationship with affiliation organizational commitment and trust to coworkers. Results: In order to develop citizenship Participation and Meritocracy, attention to organizational structure, specifically bureaucratic organizations, seems to be essential for future in Iran.