Organisations are increasingly looking beyond their organisational boundaries to evaluate how resources can be utilised to survive and grow the business. Different inter-organisational relationships have emerged as important resources in supply chains. The decision about what type of inter-firm relationship is appropriate for a specific circumstance appears complex and demands a particular degree of managerial attention. Supply chain researchers agree that in many instances, not all inter-firm relationships need to be either cooperative or collaborative and that there is no unique relationship suitable for all circumstances. While marketing channel theories and supply chain theories can provide some explanation for a wide range of inter-organisational relationships, the existing literature lacks a comprehensive explanation of the interplay between the attributes of relationships, the desired outcomes and differing inter-firm relationships. Consequently, this research seeks to fill the gap in the literature by first explaining the power that relational factors such as trust, power, interdependency, longevity and sharing, have in predicting the types of inter-firm relationships a firm participates in and, second, by understanding and discussing the linkages between achieved benefits, such as reduced costs, improved quality, flexibility, speed and reliability of an organisation involved in an array of relationships. In order to address the gap a theoretical framework was tested through a three stages methodology, which involved convergent interview, self-administered questionnaire and a case study. Qualitative data was analysed by using content analysis techniques in which patterns were identified from the data while quantitative data was analysed using confirmatory factor analysis and multiple regression analysis. The road freight transport industry was chosen as the research setting to examine inter-organisational relationships because of its complexity and competitiveness in the Australian setting. This thesis concludes that trucking firms are only marginally shifting from loose to closer relationships, so they tend primarily to be adversarial players and as such expect to achieve four primary outcomes. These are improvements in operational cost, flexibility, quality and reliability.-- Abstract