‘Theories and neurobiology of development’ defines what a theory is and examines how the theories of two famous psychologists, Piaget and Vygotsky, have aided the current understanding of child development. Classically, theories of child development were based on observations of child behaviour. Piaget focused on the growth of logical thinking and Vygotsky looked at the influence of culture and language on child development. More recent ideas from neurobiology, particularly in brain imaging and genetics, are changing the way we look at child psychology. However, information from neuroscience will never replace the importance of understanding child development at the psychological level.