Rachel McMillan was born in New York on 25th March, 1859. Her sister, Margaret McMillan, was born the following year on 20th July, 1860. Their parents, James and Jean McMillan, had originally come from Inverness but had emigrated to America in 1840. In 1865 James McMillan and his daughter Elizabeth died. Margaret also caught scarlet fever and although she survived it left her deaf (she recovered her hearing at fourteen).
Deeply upset by these events, Mrs. McMillan decided to take her two young daughters back to Scotland. Rachel and Margaret both attended the Inverness High School and were able to make good use of their grandparents well-stocked library. When Jean McMillan died in 1877 it was decided that Rachel would remain in Inverness to nurse her very sick grandmother, while Margaret was sent away to be trained as a governess.
In 1887 Rachel paid a visit to a cousin in Edinburgh. Her cousin took her to church where she heard an impressive sermon by John Glasse, a Christian Socialist. Rachel was also introduced to John Gilray, another recent convert to this religious group. Gilray gave Rachel copies of Justice, a socialist newspaper and Advice to the Young, a book by Peter Kropotkin. Rachel was impressed by what she read. She particularly liked the articles by William Morris and William Stead.
During the following week Rachel went with Gilray to several socialist meetings in Edinburgh. When she arrived home in Inverness she wrote to a friend about her new beliefs: "I think that, very soon, when these teachings and ideas are better known, people generally will declare themselves Socialists."
Rachel's grandmother died in July 1888. Freed of her nursing responsibilities, Rachel joined Margaret McMillan in London and the two remained together for most of the rest of their lives. Margaret, who was employed as a junior superintendent in a home for young girls, found Rachel a similar job in Bloomsbury.
In London Rachel and Margaret attended socialist meetings where they met William Morris, H. M. Hyndman, Peter Kropotkin, William Stead and Ben Tillet. They also began contributing to the magazine Christian Socialist and gave free evening lessons to working class girls in London. Margaret later wrote: "I taught them singing, or rather I talked to them while they jeered at me." It was at this time that the two sisters became aware of the connection between the workers' physical environment and their intellectual development.
In October 1889, Rachel and Margaret helped the workers during the London Dock Strike. The continued to be involved in spreading the word of Christian Socialism to industrial workers and in 1892 it was suggested that their efforts would be appreciated in Bradford.
Although for the next few years they were based in Bradford, Rachel and Margaret toured the industrial regions speaking at meetings and visiting the homes of the poor. As well as attending Christian Socialist meetings, the sisters joined the Fabian Society, the Labour Church, the Social Democratic Federation and the newly formed Independent Labour Party (ILP).
Margaret and Rachel's work in Bradford convinced them that they should concentrate on trying to improve the physical and intellectual welfare of the slum child. In 1892 Margaret joined Dr. James Kerr, Bradford's school medical officer, to carry out the first medical inspection of elementary school children in Britain. Kerr and McMillan published a report on the medical problems that they found and began a campaign to improve the health of children by arguing that local authorities should install bathrooms, improve ventilation and supply free school meals.
The sisters remained active in politics and Margaret McMillan became the Independent Labour Party candidate for the Bradford School Board. Elected in 1894 she was now in a position to influence what went on in Bradford schools. She also wrote several books and pamphlets on the subject including Child Labour and the Half Time System (1896) and Early Childhood (1900).
In 1902 Margaret joined her sister Rachel in London. The sisters joined the recently formed Labour Party and worked closely with leaders of the movement including James Keir Hardie and George Lansbury. Margaret continued to write books on health and education. In 1904 she published her most important book, Education Through the Imagination (1904) and followed this with The Economic Aspects of Child Labour and Education (1905).
The two sisters led the campaign for school meals and eventually the House of Commons became convinced that hungry children cannot learn and passed the 1906 Provision of School Meals Act. The legislation accepted the argument put forward by the McMillan sisters that if the state insists on compulsory education it must take responsibility for the proper nourishment of school children.
In 1908 Rachel and Margaret McMillan opened the country's first school clinic in Bow. This was followed by the Deptford Clinic in 1910 that served a number of schools in the area. The clinic provided dental help, surgical aid and lessons in breathing and posture. The sisters also established a Night Camp where slum children could wash and wear clean nightclothes.
Rachel and Margaret McMillan both supported the campaign for universal suffrage. They were against the use of violence and tended to favour the approach of the NUWSS. However, they disagreed with the way WSPU members were treated in prison and at one meeting where they were protesting against the Cat and Mouse Act, the sisters were physically assaulted by a group of policemen.
In 1914 the sisters decided to start an Open-Air Nursery School & Training Centre in Deptford. Within a few weeks there were thirty children at the school ranging in age from eighteen months to seven years. Rachel, who was mainly responsible for the kindergarten, proudly pointed out that in the first six months there was only one case of illness and, because of precautions that she took, this case of measles did not spread to the other children.
Rachel McMillan, who had suffered from poor health for a long time, died on 25th March, 1917.