Although information technology outsourcing (ITO) is a major part of an organization’s IT strategy nowadays, many ITO engagements in practice still fail to meet their goals. Past research on ITO iden-tified the ITO client-vendor relationship as one of the key antecedents for ITO engagement success. Despite this known relationship, a detailed understanding of factors contributing to the establishment and maintenance of ITO relationships from both the client and the vendor perspective is still missing. Our study sheds light into this important topic by identifying, comparing, and categorizing 104 factors concerning the ITO client-vendor relationship based on an empirical study. Our study applies Kelly’s personal construct theory by using the repertory grid (RepGrid) method for identifying factors from both the client’s and vendor’s perspective. Based on our study design, we were able to identify common as well as diverse viewpoints with regard to the ITO client-vendor relationship. Together with a cate-gorization of the factors based on the ITO relationship model of Kern and Willcocks (2000), we provide important insights into the successful structuring of the ITO client-vendor relationship in practice as well as interesting avenues for further research on this topic.