English social worker and educationalist, of Scottish origin. She was largely responsible for establishing the first recorded medical inspection of school children in 1899 and was, with her sister Rachel, a pioneer in social work, children's education and teacher training.
She was born in Westchester, New York State, of Scottish parents, and was educated in Scotland and Switzerland. In 1893 she arrived in Bradford and joined the newly formed Independent Labour Party. The following year she was elected to the local school board. In 1902 she joined her sister, Rachel, in London. Together they opened children's clinics at Bow (1908), and Deptford (1910). The latter received grants from the London County Council for dental treatment (1911) and eye and ear treatment (1912). It was linked with a nursery school for infants and a camp for boys and girls. During World War I the sisters founded an open-air nursery school for children under five years old. In 1923 she became the first president of the Nursery School Association. At this time she turned her attention to teacher training. From the nursery school she founded grew the Rachel McMillan College (named after her sister who had died in 1917) which was opened in 1930. In 1936 the college extended its activities by setting up a holiday house for Deptford nursery school children at Wrotham, Kent. Margaret McMillan was awarded the CBE (1917), and appointed a Companion of Honour (1930). Her publications include Early Childhood (1900), Labour and Childhood (1906), The Child and the State (1911), The Camp School (1917), and The Life of Rachel McMillan (1927).