The continued growth of IT outsourcing suggests that it is an important strategic alternative that cannot be simply ignored. However, research has been heavily biased towards the client's perspective, with little work being done from the vendor's perspective, even though outsourcing is essentially an interorganizational relationship that involves two parties. The primary objective of this thesis is, therefore, to provide a balanced view by looking at the duality of IT outsourcing, to address the broad research question: How successful is IT outsourcing, from both the client and vendor perspective? This is done through two separate but related studies that focus on the duality of IT outsourcing. The first essay uses psychological contract theory to study IT outsourcing management from a dual perspective. Research has focused on antecedents to outsourcing, and comparatively few studies have looked at managing of the relationship. Essay 1 addresses this gap by studying outsourcing management through a psychological contract lens that focuses on mutual client-vendor obligations. Using a sequential, qualitative-quantitative approach, I identified these obligations, and demonstrated empirically their impact on success. Content analysis of interview transcripts from the qualitative study showed that both clients and vendors identified six obligations from each other that are critical to success. Results from the second quantitative study showed that fulfilled obligations predicted success over and above the effects of project type, duration, and size.