Despite the fact that firms and individuals have been sourcing on a global basis since ancient times, global sourcing as a topic has received considerable attention from managers and scholars in recent years. Global business has been reported to be growing considerably during the last decades and the trend continues; hence a scientific examination of global sourcing performance and success factors is timely and appropriate. This dissertation explores some of the effects, the success factors, as well as the threats of global sourcing. Particular attention is paid to performance evaluation and integration as a prerequisite for successful global sourcing. It consists of four independent scientific papers connected by means of a coherent thematical bracket. The first two papers address the perception of global sourcing as a purchasing panacea, and compare it to real results from global sourcing. The last two chapters explore the role of the buying companies' internal and external integration with suppliers, giving insight into performance results from integration. The research was performed with a triangulation of methods, notably findings from qualitative and quantitative research, based on primary and secondary data.