This book is essentially the third volume on the history of British Petroleum (BP) from 1901 to 1975, which the author has tried to present on its own, to be read with or without reference to the previous two volumes. It deals with three phases of BP's developments during 1950–75, starting with the 1950–54 period of Iranian oil-nationalization crisis, the 1955–70 phase of growth and internationalization, and finally the 1974–75 takeover by the Organization of Petroleum Exporting Countries (OPEC). The author has been BP's “official historian” for years, and the company's “History Committee” has approved the present study.