Maria Montessori stands out among the people who participated in the creation of modern education. The preschool age in which true learning takes place was viewed as a critical stage in the development of an individual during which the foundation for all future development is established. This paper explores the influence of the Montessori pedagogy on the child's positive self-image. The theoretical part of the paper gives insight into the extraordinary contribution of Maria Montessori to modern pedagogy and explains the basic principles of the Montessori pedagogy. Furthermore, it explains the image of one’s self and the ways of encouraging the development of a positive image of one's self. In the research part of the paper, the aim was to determine what kind of image the participants of the Montessori program have about themselves in relation to regular preschool participants, and the educators’ assessment of the children's cognitive and physical achievements and peer acceptance. A total of 52 children from Montessori and mixed-age group of Požega kindergarten participated in the study. The results show that there are no significant differences in the self-assessment between the children of the Montessori program and regular program participants. Educators estimate the cognitive competences of children lower than the children themselves in both programs. The obtained results indicate that children in both groups estimate their cognitive and physical competences as being relatively high, and the lowest results are related to peer support.