Piaget was born in Neuchâtel, Switzerland in 1896 and famously began his scientific career aged 10, when he published a paper on his observations of an albino sparrow. He continued to publish work (on molluscs) during high school, and his work became well known to many students across Europe who were ignorant of the fact he was still a child. His interest in natural history and biology combined with a crisis of faith during his adolescence lead him to search for a 'biological explanation of knowledge'.
He attended the University of Neuchâtel until 1918 when he received his Doctorate in Science. This was followed by a short spell working in the psychology laboratories in Zurich and in a famous psychiatric clinic. After this he taught psychology at the Sorbonne in Paris, where he met Théodore Simon and came to work on Binet and Simon's team developing the first valid measure of general 'intelligence'. However, he was interested by the nature of the children's answers, correct and incorrect, and what these could tell us about changes in cognitive processes as children grow older. He began interviewing the children he worked with, using the techniques he had learned the year before. In this way he was one of the first developmental psychologists to move attention away from 'outcomes' (what children can achieve) to 'processes' (the underlying mechanisms that facilitate or inhibit achievement).
In 1921 he moved to the Institut J.J. Rousseau in Geneva and began (with his students) to research the reasoning of primary school children, having published his first article on the psychology of intelligence. Five books on child development followed based on this work. In 1923 he married one of his student collaborators, Valentine Châtenay, with whom he had three children: Jacqueline, Lucienne and Laurent. Piaget and his wife began systematic observations of their children, which were to form the basis of another three books on child development. Between 1929 and 1949 he took up a number of influential academic posts while becoming increasingly involved in the work of UNESCO. In 1949 and 1950 he published Introduction to Genetic Epistemology, and finally created the International Centre for Genetic Epistemology in 1955.
Piaget's theoretical contribution is still regarded as a cornerstone of modern developmental psychology, although much of his empirical work is criticised on methodological grounds. He is also significant for working collaboratively with female psychologists at a time when this was still exceptional. Piaget died in Geneva in 1980.