This chapter provides literature-grounded definitions of contemporary Web services and marketing theories, which can model business demand through procurement decision-making behavior. First, the literature was reviewed to identify contemporary Web 2.0 and Web service ontology alongside marketing theories, which can describe individual decision making in an organizational or personal context. The Web services included cloud computing, social networking, data storage, security, and hosted applications. Then selected models for assessing procurement decision-making behavior were discussed in more detail. The constructed grounded theory method was applied by interviewing Chief Information Officers (CIO) at large organizations across four industries in the USA: healthcare, higher education, energy creation, and banking. The purpose was to determine which marketing theories could effectively model their Web service procurement behavior. An empirical procurement decision-making model was developed and fitted with data collected from the participants. The results indicated that Web service procurement decision-making behavior in businesses could easily be modeled, and this was ratified by the CIOs. The chapter proposes a state-of-the-art ontology and model for continued empirical research about organizational procurement decision-making behavior for Web services or other products.