Today, Web services are of interest to both academia and industry. However, little has so far been accomplished in terms of design and development methods to assist those who are responsible for specifying and deploying applications based on Web services in compliance with service computing principles. For this purpose, the authors developed in this chapter a method based on Context and Policy for Web Services known as CP4WS. In this method, policies manage various aspects related to Web services such as participation in composition scenarios and adjustment in response to environmental changes, and context provides the necessary information that permits for instance to trigger the appropriate policies and to regulate the interactions between Web services with respect to the current state of the environment. CP4WS consists of several steps such as the identification of user needs and the behavioral specification of Web services. Each step has a specific graphical notation that facilitates the representation, description, and validation of the composition operations of Web services. A case study that illustrates and highlights the use and originality of CP4WS, respectively, is provided in this chapter.