In this article, I explore the role that analogical reasoning plays in the developing thought of the child. Analogical reasoning is defined as the process of identification and transfer of a relational structure from a known system (the source) to a less known system (the target). This process is more general than metaphor and can apply even between systems that belong to the same category. I argue that this process is fundamental to the acquisition and use of external representational systems such as oral and written language, arithmetic, and music and is thus an important aspect of cognitive development. The acquisition and use of external representational systems depend on the identification of correspondences between the representational system and the physical and social environment or on the identification of correspondences among different representational systems. The acquisition and use of such systems also depend on the transfer of information from one representational system to another and on the evaluation of the applicability of the information transferred for the system concerned. (Stella Vosniadou)