It is generally accepted that the curriculum is a scientific conceptualisation of goals, tasks, contents, plans and programs, organizations and technologies for conducting selected contents, pedagogical activities and different forms of evaluation. The curriculum of early and preschool education is open, dynamic and subject to changes within the institution for early and preschool education. It stems from learning, research and cooperation of all the participants in the educational process. Since the curriculum of early and preschool education is understood as a complex system in terms of structure, this paper starts from the assumption that the structure and content of the curriculum intertwine with the cultural components of the institutions for early and preschool education. The culture of the institution consists of the spatial-material environment, organization of time, social relations and communication, as well as the values, beliefs and attitudes of adults and children. This research sought to contribute to the elucidation of conditions that enable the continuous transformation of educational practices and the development of the curriculum. Based on those propositions, this paper emphasizes the participative, collaborative and self-reflective nature of action research with the aim to improve the quality of educational practices and curricula. The research was conducted in the Kindergarten “Zvrk” (in Đakovo and Vrpolje). All educators and the principal participated. The aim of the research was to examine the development of research and reflective skills of educators that are necessary for the development of structural and content determinants of the curriculum. The paper presents an analysis and argumentation of different, very flexible roles of educators in the context of contemporary pedagogical views. Theoretical analysis of the relevant scientific literature demonstrated that the structure and content of the curriculum of early and preschool education are influenced by childhood paradigms (image of the child), the role of educator (his/her implicit pedagogy), characteristics (culture) of the institution and the social context. The determinants are interdependent, and the results of this research emphasize that a continuous rise of the quality of educational practices and co-construction of the curricula could be achieved by the shift of the determinants. Empirical analysis of the conducted action research points to the changes in all mentioned structural determinants of the curriculum, as well as changes in the perception and acceptance of children’s positions and their ways of learning, educators' beliefs and culture of the institution. Participation in action research, continuous professional learning capabilities and advancement, reflections of the educator's own work and evaluation of his/her efficiency in collaboration with other educators coincide with the transformation of the institution for early and preschool education into and a learning community.