Joseph Houldsworth Oldham, pioneer of ecumenical missionary and social concern, was born in 1874 of Scottish parents in India. He was educated in Edinburgh and at Oxford, from where he graduated in 1896. A religious conversion prompted Oldham to travel to India in 1897 to work with the YMCA where he stayed for three years, marrying Mary Fraser in 1898. Illness forced them to return in 1901 and Oldham went on to study theology at New College, Edinburgh and in Germany. On his return to Scotland he was twice an assistant minister but was unable to secure his own ministry. In 1908 he became organising secretary for the 1910 World Missionary Conference at Edinburgh, regarded by many as the starting point of the modern ecumenical movement, and he was subsequently secretary of the Conference Continuation committee. In 1912 Oldham founded the International Review of Missions which, under Oldham's editorship until 1927, established itself as the most prominent missionary periodical in the world.

During World War 1 Oldham worked to keep the spirit of internationalism alive through his writings and became a trusted adviser of the government on missions and German missionaries in particular. With the return of peace Oldham continued to promote the cause of co-operation between mission boards. He became the founder and secretary in 1921 of the International Missionary Council. He also travelled widely (often with his secretary Betty Gibson) and was especially concerned with education and the issues raised by colonial administration in Africa. His knowledge of both India and Africa thrust him into the role of mediator between Europeans, Africans and Indians in Kenya and his principle that African native interests should be paramount was embodied in government policy in 1923. Also in that year Oldham was a key figure in the establishment of a committee on Native Education in Tropical Africa. His Christianity and the Race Problem was published in 1924 and was his most substantial and successful book. After organising the first conference of missionary educators and colonial administrators in 1926, he was instrumental in securing funds for the founding of the International Institute of African Languages and Cultures.

From 1931 to 1938 he was its administrative director and responsible for much of the work which made Lord Hailey's African Survey possible. Oldham continued, often in partnership with Lord Lugard, to advise on government and administration in Kenya, however he also remained concerned about the future of the Christian missions and the church. As a layperson Oldham grew more convinced of role of the laity in this future and the need for a co-operative relationship between religious and secular groups and, to this end, encouraged small study groups as a means of research. He was, from 1934, chairman of the research committee of the Universal Christian Council for Life and Work and a key figure at the 1937 Oxford conference. His efforts were to influence Christian thinking for a generation and lead to the formation of the World Council of Churches. During the Second World War he continued to encourage debate about lay responsibility in society. Through the meetings of his 'Moot' with such figures as T.S. Eliot and John Baillie and through his Christian Newsletter he initiated much new thinking about Christian responsibility in modern society. From his efforts the Christian Frontier Council developed. Oldham retired from public life to Dunford, Sussex but continued to write, particularly about Africa, and was involved with the formation of the Capricorn Africa Movement. He was awarded honorary degrees from Edinburgh (1931) and Oxford (1937) and appointed CBE in 1951. Oldham's wife died in 1965 and Oldham himself died in 1969 at St Leonards-on-Sea, Sussex.

Betty D. Gibson was one of the secretarial staff of the International Missionary Council in which she played a significant role acting as secretary and administrator for both the IMC and for Joseph Oldham. A graduate in French and German, in 1916 she joined the staff of Oldham's Continuation Committee which had been set up after the 1910 World Missionary Conference. She made several trips overseas for missionary conferences or to investigate the state and extent of missionary activity in various countries and kept in close contact with Oldham throughout.