The granite island was bought by the Nature Conservancy Council (now Scottish Natural Heritage) in 1957 to be a National Nature Reserve. It contains the Edwardian Kinloch Castle dwelled in by the Bulloughs, made of red sandstone from Annan.
Rum is now an important study site for research in ecology. Its Red Deer population have been the subject of study for many years, recently under the leadership of Tim Clutton-Brock. This study has been important in the development of sociobiology and behavioral ecology, particularly in relation to the understanding of aggression through game theory, i.e. the theory of the evolutionarily stable strategy as developed by John Maynard Smith.
The island came to widespread attention with the 2000 publication of the book A Rum Affair by Karl Sabbagh, a British writer and television producer. The book told of a long-running scientific controversy over the alleged discovery of certain plants on Rhum by botanist John Heslop Harrison - discoveries that are now considered to be fraudulent. Heslop Harrison is widely believed to have placed many of these plants on the island himself, to provide evidence for his theory about the geological development of the Hebrides islands.