Purpose: This study examines the social organizational structure of one early childhood education (ECE) center in Finland and the relationship between this structure and the roles and the responsibilities of the members of the organization. Design/methodology/approach: The research is a qualitative case study with ethnographic features. Its variables for content analysis are based on Henry Mintzberg's theory of organizational design. Findings: The study's results show that the organizational structure of the ECE center follows the organizational configuration of a Professional bureaucracy and that the multiprofessional teams follow the configuration of a Simple structure. The structures for centralization and decentralization are suitable for a professional bureaucracy, but the roles of the members of the organization and the processes for shared decision-making lack clarification. The shortage of qualified ECE teachers disrupts the function of the organization and the work of ECE leaders. Research limitations/implications: The educational background of subjects may have affected the findings. Originality/value: The study uses Henry Mintzberg's organizational structure theory to evaluate how and why power is distributed and activities are coordinated at the ECE center. The results also show what parts of the organization pose challenges that most commonly disrupt the organization's operations. With these findings, it is possible to expand the understanding of roles and responsibilities in the currently reforming ECE environment and what ECE centers need to function effectively. The study is part of a larger research project and will be continued to examine the leadership culture of the ECE center.