Maria Montessori and Jean Piaget were contemporaries which left a mark which is visible even today, thanks to their educational theory and practice, but also their outlook on the child itself. Thus, the main goal of this paper was to compare similarities and differences in work by these two scientists, regarding their observation methods, outlook on child development and their educational approach and work. Bearing in mind that Piaget was a director of Swiss Montessori Society, it should be a no surprise that there are numerous similarities in their work. However, there is equally a vast number of differences in their educational and psychological approaches which are best visible in the research techniques they used, as well as in their view on certain aspects of child’s cognitive development. Final difference lies in their elaboration of applicable educational guidelines in Montessori education, which were left on primarily theoretical level when it comes to Piaget. What connects these two scientists is the fact that they both argued against memorizing and reproducing factual knowledge, and promoted child-centered education instead. Furthermore, Montessori and Piaget both advocated self-directed learning, encouraged child’s independence, responsibility, creativity and overall autonomy of a child, along with placing emphasis on the importance of stimulating learning environment.