Self-evaluation refers to the ability to assess one's own possibilities, successes and achievements, and primarily work on oneself. It contributes to encouraging and developing a positive self-image, strengthening self-confidence, critical thinking, respect for diversity and encouraging the development of responsibility for decision-making and own actions. It represents the basis for lifelong education and is a means of developing the competences of responsibility, both towards oneself and towards others. It is a cyclical process of acquiring knowledge, testing what has been acquired, analyzing performance and looking for upgrade opportunities in order to encourage further development. The possibilities of children's selfevaluation in early and preschool age are very poorly researched, mainly because of the prejudice that children of that age are too young, or because of the difficulty of creating and applying suitable tools for self-evaluation; although contemporary understandings of the child emphasize the importance of acquiring self-evaluation skills from an early age. Therefore, this action research attempted to determine whether children of early and preschool age can selfassess, in what way, at what age and with what tools. Tools for self-evaluation were developed: a traffic light scheme for understanding the instructions and an emoticon scale for self-evaluation of success after the implementation of the activity, which were then offered to the children for use and tested. The goal was to investigate the possibilities of children's selfevaluation in early and preschool age, for children in educational groups aged three to seven years. Children's self-evaluation was recorded with teacher's notes, audio recordings, photo documentation and conversations with children (children's explanations/reflections). The research was conducted from the beginning of November 2022 to the end of January 2023. The results of the research showed that children are capable of self-evaluation, but it is necessary to work intensively on it, to remind them of the meaning of the tools and to constantly offer them from an early age, with the adjustment of levels divisions of selfevaluation according to age.