This classic and hence still popular book is written by Arnold Gesell.
He is one of the pioneers of child development theory and a champion of individuality, Arnold Gesell introduced an entirely new view of child development.
After receiving his Ph.D from Clark University, in 1906, he served as an assistant professor at Yale University. While there, he developed an interest in physiology and continued his studies and received his M.D. in 1915.
Gesell’s Maturational Theory of child development led to the publication of the Gesell Developmental Schedules, which summarized descriptions of each developmental stage and its sequence. One of the greatest benefits his research had on modern developmental parenting styles was freeing parents from the anxiety caused by rigid, age-based theories of development.