This paper presents CP4WS (standing for Context and policy for Web services), which is a context-based and policy-driven method for the design and development of Web services-based systems. Although Web services constitute an active area of research, very little has been achieved for the benefit of those who are responsible for modeling and developing such systems. To address this lack of support, we developed CP4WS that consists of several steps ranging from user needs identification to Web services behavior specification. A running scenario that illustrates the use of CP4WS is also discussed in the paper.