Mark Casson pioneered the use of transaction cost theory to explain the boundaries of the multinational firm. In The Organization of International Business, he extends the internalization theory of the firm to encompass, on the one hand, inter-firm networking and, on the other, the internal organization and managerial structure of the firm. The key innovation is the distinction between information cost - the cost of gathering information on the assumption that it is true - and transaction cost - the cost of ensuring that the information actually is true. This innovation facilitates a synthesis of transaction cost analysis and organizational behaviour. It also provides new insights into the dynamics of internationalization, and the role of learning in the growth of the firm.