INTRODUCTION: The Red Crescent Society of the Islamic Republic of Iran is one of the most effective service-oriented organizations in the country which has a high potential for trust building and role modelling. Using human resources with a humanitarian approach and identification of causal, contextual, and intervening factors that lead to building trust contribute to the excellence of this popular institution. Therefore, this study aimed to present a model of organizational trust based on the assumptions of human resources in service-oriented organizations, particularly The Red Crescent Society of the Islamic Republic of Iran, using the meta-synthesis approach. METHODS: This is a qualitative cross-sectional study, in which 1,269 relevant articles published between 2010 and 2022 were collected from the Web of Science database. A total of 85 articles were selected and used, as the basis for the data extraction, to determine trust building based on the assumptions of human resources theories in the interpretive paradigm. FINDINGS: Trust building in the Red Crescent Society is one of its essential elements due to the impact of environmental and human variables. Therefore, this study identified causal conditions (organizational factors, job, employees), background conditions (culture, ethics, religion, individual, organization, intervening conditions (managerial, occupational, and psychological), strategies (new leadership, transparency, Quantum management, talent management), and the outcomes (including organizational citizenship behaviour, social responsibility, organizational spirituality), which included a total of 28 common features and 152 components. CONCLUSION: Based on the obtained results, trust-building management methods in the Red Crescent Society include open communication, brainstorming, collaborative management, a supportive atmosphere, and effective strategies in the functional dimensions of the Red Crescent Society, including new leadership, behavioural assumptions of managers, as well as decision-making in terms of content, time, model, cognition, and approaches of transformative leadership, ethical and pure leadership, positive and servant leadership, and distributed and intellectual leadership.
