The focus of this thesis is to understand the initial formation of inter-firm relationships with the aim of establishing a long-term relationship in the offshore-wind sector. It is common to initiate relationships with pre-existing partners but less is known about how firms form relationships with strangers. This thesis attempts to answer a research question: 'How and why new inter-firm relationships are built in nascent industries with highly uncertain business environments?' The research involves three longitudinal case studies (12 pairs of supplier-buyer relationships) of three offshore wind (OSW) suppliers and one OSW buyer, and their relationships with new partners in a highly uncertain market and political context. By examining the early-stage relationships between a supplier and multiple new customers this study provides insights into supplier selection in the OSW sector. It identifies the main motivations for OSW supply chain companies seeking new partnerships and how they benefit from the new relationships despite facing high market risk and political uncertainty. Furthermore, this research reveals how inter-firm relationships progress (or fail) from one stage to another under high market risk and political uncertainty. This study argues that the way the selective process is being managed is as important as the levels of compatibility and complementarity and makes theoretical contributions on how to achieve greater understanding and knowledge advancement of dynamic relationship life-cycle management, effects of compatibility and complementarity, uncertainty and time series dimensions are made.