The purpose of this study was to explore and delineate the curriculum of global citizenship education in elementary schools of Iran's educational system and to develop an exploratory model. In this exploratory research, based on the grounded theory, semi-structured interviews were conducted with 34 active members in the field of global citizenship. The themes and sub-themes of the curriculum of global citizenship education and their associations were explored within three steps of open, axial, and selective coding. To generalize the results of the qualitative phase and to validate the resulting model, a questionnaire was designed and completed by 387 elementary school teachers in Tehran, Iran. The analysis process in the qualitative phase included twelve themes of attention to necessity, goals, content, teacher's role, teaching-learning methods, evaluation, time, location, materials and resources, organizational factors, implicit learning, and program outcomes. In the quantitative phase, the hypotheses derived from the qualitative analysis were confirmed. Finally, according to the findings and the results, some guidelines are provided for implementing the program.