Learning local languages, he was appointed head of the Anthropological Department of Asante in 1921.
With his office in the Anthropological Department in Ashanti, Rattray set out to do detailed and voluminous research on Ashanti religion, customs law, art, beliefs, folktales, and proverbs.
His personal contact with the people of Ashanti afforded him an intimate knowledge of their culture, which is reflected in his thoughtful and nuanced writing on them.
"[4] Like many anthropologists of his day, Rattray collected many ethnographic artefacts during his time in Africa, took photographs, collected folk tales and language information and experimented with sound recording.
[6] His fieldwork papers are held in the archives of the Royal Anthropological Institute (UK).