Information System (IS) effectiveness assessment is an important issue for the organizations as IS have become critical for their survival. With the incorporation of Internet technologies into the business environment, it is now more difficult to measure IS effectiveness, because Internet provides a borderless, non-stop, flexible communication medium. Assessing the effectiveness of web-based information systems (WIS) is vital for survival and competitive advantage which is a complicated subject since there are several interacting factors to consider. In the literature there are several methods proposed for IS assessment. However, those studies have been far from providing a broad, comprehensive evaluation framework for any type of web-based IS independent of its domain. In this book, a generic WIS effectiveness assessment framework is proposed. The framework is applied in case studies consisting of four organizations in e-commerce and e-banking domains.