This paper states and describes age-mixed groups and the characteristics of organizing and conducting art activities in them. Katz et al. (1991) describe mixed-age groups as groups in which children with a one-year age difference are grouped together. Working with such groups requires high-quality education and competence of educators in the knowledge of art education and the art language of children of early and preschool age in order to be able to provide and enable equal opportunities for children of different ages and support their overall development within the group. This paper presents art activities conducted in a mixed-age group attended by children from 3 to 7 years of age. The elements and stages of the development of children's artistic expression and the specifics of performing art activities in mixed age groups are visible in the activities carried out. Furthermore, this work tried to examine the opinions and experiences of educators in working with children of mixed age groups. The goal of this research is to determine, according to the educator, the differences in organizing and conducting art activities in age-mixed groups compared to homogeneous groups, and to determine the differences in children's behavior during art activities in age-mixed groups compared to homogeneous groups. Twelve educators from Međimurje County were included in the research, and the measuring instrument used was a survey questionnaire. The first and third hypotheses were confirmed, in which educators emphasize the role of planning activities in accordance with developmental needs in age-mixed groups as the most different compared to homogeneous groups, and educators observe more developed social behaviors (cooperation, prosocial behaviors) in children in age-mixed groups compared to homogeneous groups. The second hypothesis was rejected because educators do not notice significant differences in the choice of topic, motive, technique and motivation in age-mixed groups compared to homogeneous groups. Also, educators do not notice significant differences in the organization and conduction of art activities in age-mixed groups compared to homogeneous groups, but they notice differences in children's behavior, which partially confirms the main hypothesis.