Many companies utilize employee portals to improve their information exchange, communication, and employee collaboration, as well as to better support their business processes. Owing to limited IT budgets and the need to justify investments into employee portals, assessing the benefits of these is an important field in research and practice. The overall purpose of this study is therefore to gain a better understanding of employee portal success. As a starting point, existing research on information systems success was analyzed. Subsequently, a theoretical model was developed which captures the different determinants of employee portal success and their interrelations. After the foundations of structural equation modeling using partial least squares had been outlined, the proposed model was empirically tested, using survey data collected within a benchmarking study. Complementary to the causal analysis, the improvement potentials of the success dimensions were further investigated within a performance-based analysis. Overall, this book addresses a number of research questions in the area of employee portal success and contributes to a deeper understanding of that field.