Abstract – The study described in this paper is a part of a cross-sectional study which focuses on Greek children in preschool and middle school age and to primary school teachers' concepts and classifications regarding animals and the associated values attached in concepts and classifications; i.e. which entities categorize as animals and which are the categorization criteria they use and if they differ with the course of age. The research was conducted with group and individual interviews and proper modifications of Interview about Instances (IaI) technique. Various groups of children and primary school teachers as a representative group of adults were interviewed for the meaning of the concept "animal", and the constant comparative method was employed to analyze data. Key findings in children ideas are the recording of a limited range of entities, which are categorized as animals, the use of sensory criteria mainly for deciding about the categorization, and especially the humanoriented course of perceptions. Findings indicate that the meaning of the concept of "animal" that both, children and teachers possess is restricted and anthropocentric, as it appears a universal denial of human categorization in animal kingdom. Nonetheless, it seems that the anthropocentric ideas of school children and adults differs qualitatively, as school children, besides taking more anthropocentric stands compared to adults, they are not led so much by ideological and ethical motives in their decisions, a fact that seems to be developed in lateral stages of life. Keywords – Preschool Children, Primary School Pupils, Primary School Teachers, Ideas, Conceptions, Animal.