Retta Dixon became a Baptist missionary at the age of nineteen with the New South Wales Aborigines Mission. Her first appointment was at La Perouse at Botany Bay and she preached along the coast of New South Wales. In 1899 the Mission was renamed the New South Wales Aborigines' Mission. In 1905, Dixon left the organisation to form the Aborigines Inland Mission (AIM), of which she appointed herself Director. In 1906, Dixon married Leonard Long. Long and Dixon were co-directors of AIM and worked as superintendent and matron of the Singleton Girls' Home until 1910.