Internationalization of industries, international competition, and the deregulation and harmonization within the EC are some of the important factors changing the prerequisites and requirements for effective international transport systems. Thus there is a need for more articulated knowledge regarding the internationalization processes of freight transport companies. In this longitudinal study the internationalization processes of three of the largest freight transport groups in Sweden have been analyzed in terms of changes in foreign representation: agents, join ventures, sales offices, subsidiaries. In addition, the relational effects of these changes on suppliers, owners, and competitors have been analysed. The results show that internationalization patterns change over time. First there was a gradual change of single relationships and systems. As an increasing number of transport companies became internationalized, there was a shift into more leapwise changes of nets of related companies. Furthermore the patterns and effects of internationalization differed between the three cases depending on when their internationalization process started. Typical sequences of changes have been identified to occur over time. As international interconnections between transport companies has increased these sequences have induced the development of domino effects in the network of transport companies. Based on the findings in this dissertation a dynamic model of internationalization is formulated. The model synthesizes the basic driving forces derived from network, distribution and internationalization research / Diss. Handelshögsk. : Stockholm