The Iban or the Sea Dayaks of Sarawak have probably been the best known of the indigenous peoples of Borneo for well over a century. Much has been written about them, but until the results of Dr Freeman's field research were published by the Government of Sarawak and by Her Majesty's Stationery Office in 1955 there was little information on their methods of agriculture and their social system. The book has become a landmark in the studies of shifting cultivation and of cognatic kinship organization; and the ideas around which it is written have proved over the years to be a continuing and powerful stimulus in the development of kinship theory. The field work on which the account is based was undertaken from 1949 to 1951. Although fundamental changes have taken place in the life of the Iban since the book was first published, it has been decided to republish it substantially unaltered.