The increased interest of politics and the practice of ECCE on the issue of the participation children in their own lives is a consequence of changed picture of child and shifting focus on child as active participant in socio-cultural reality instead of earlier focus on individual development of child. The Convention on the Rights of the Child (1989) strongly supports the image of child as a competent participant in education – able to shape opinion, with the right to express himself/herself on all issues related to them and with the right that adults in his/her environment respect that. However, regardless of the contemporary paradigm of ECCE, achievements in this area are still at very beginning. This can be seen in the practices of ECCE whereby children of early and preschool age are still viewed as users of systems and services rather than as agent of changes in their social communities. Recent literature, as an effective way to overcome the gap between theory and practice and the continuous rise in quality of ECCE institutions indicates the need for lifelong, continuous learning of preschool teachers through process of researching their own educational practice. This paper will present the process of action research with the aim of increasing the participation of children in the (co)construction curriculum of kindergarten and cooperation in decision-making on issues related to their stay in the institution. This action research took place in 2 objects of the ECCE institution – DV Rijeka. In this research participated 5 preschool teachers which work in 4 educational groups where are enrolled children at the age of 2 to 7. Also, it will be presented the process of development preschool teacher reflexive practice who participated in this research.