and Education in 1923, The Mental Growth of the Preschool Child in 1925 (which was also published as a film), and An Atlas of Infant Behavior (chronicling typical milestones for certain ages) in 1934. He coauthored with Frances Ilg two childrearing guides, Infant and Child in the Culture of Today in 1943 and The Child from Five to Ten in 1946. Gesell made use of the latest technology in his research. He used the newest in video and photography advancements. He also made use of one-way mirrors when observing children, even inventing the Gesell dome, a one-way mirror shaped like a dome under which children could be observed without being disturbed. In his research, he studied many children, including Kamala, the wolf girl. He also did research on young animals, including monkeys. As a psychologist, Gesell wrote and spoke about the importance of both nature and nurture in child development. He cautioned others not to be quick to attribute mental disabilities to specific causes. He believed that many aspects of human behavior, such as handedness and temperament, were heritable. He explained that children adapted to their parents as well as to one another. He advocated for a nationwide nursery school system in the United States. Gesell's popular books spread his ideas beyond academia. His core message, urging parents to "nourish the child's trustfulness in life", resonated with child advocates long before Benjamin Spock became America's most prominent parental advisor. In The Child from Five to Ten, Gesell wrote, "It is no longer trite to say that children are the one remaining hope of mankind... If we could but capture their transparent honesty and sincerities! They still have much to teach us, if we observe closely enough." Maturational Theory and Developmental Schedules Gesell's ideas came to be known as Gesell's Maturational Theory of child development. Based on his theory, he published a series of summaries of child development sequences, called the Gesell Developmental Schedules. The Gesell Institute of Human Development, named after him, was started by his colleagues from the Clinic of Child Development, Frances Ilg and Louise Bates Ames in 1950, after Gesell retired from the university in 1948. In 2012, the institute was renamed the Gesell Institute of Child Development. Personal In 1911, Gesell married Beatrice Chandler who was a teacher he had met while working at Los Angeles State Normal School. The couple had a daughter and a