The present study explored children’s developing conceptions of the brain in order to enhance previous research and to contribute to debates regarding the nature of children’s naïve biological theories. 56 participants aged 5, 7 and 9-years-old were recruited from 2 different primary schools within Scotland, representing a broad range of socio-economic backgrounds. Results demonstrated that young children have a restricted view of the brain, regarding it in primarily psychological terms. Additionally, results revealed that children begin to demonstrate an understanding of the physiological characteristics and functions of the brain by the age of 9 years, however, that their understanding of the brain is incomplete at this age. Furthermore, children’s understanding was found to demonstrate coherence from the age of 9 years. Stemming from the findings, the study discusses educational implications and areas for future research to explore.