This article discusses Margaret McMillan's theory of childcare education and its impact on modern day education. It covers her background, observations, and principles that are still relevant today. McMillan was a social activist, educator, and child and family advocate who fought for children's causes and developed reforms for their development. She observed the importance of developing the health of children both physically and mentally, the improper condition of slums affecting children's lives, and the need for proper interventions to make the lives of slum children better. Her principles of active learning, involvement of parents in education, and developing nutrition are still incorporated in modern day early child education. McMillan's vision has formed the foundation of early year education.