The first edition of Inside the Multinationals was a milestone book which applied the new theory of the multinational enterprises in a North American context. In it Alan Rugman popularized internalization theory. This argues that the key reason for the success of MNEs is their ability to internalize within their organizational structures, international transactions in goods and finance and thereby take advantage of the imperfections which exist in the world's markets. He helped to extend internalization theory as the cornerstone of research in the field of international business. The 1981 book has been widely cited by subsequent researchers. Although it has become a classic in the field it has been out of print for many years. Now with a new Introduction assessing the path-breaking contribution of the book, this 25th Anniversary edition gives scholars access to the original text. Professor Rugman now serves as President of the Academy of International Business.