Context-Sensitive Systems (CSS) demand that designers consider new aspects and challenges in comparison to traditional applications. In a preliminary experiment, we observed that developers have difficulties when including the concept of context in their applications. This paper presents a CSS Design Process, which details the main activities for context specification and the design of CSS and provides a systematic way to execute these tasks. Two studies were conducted to evaluate the process usage: a detailed execution of each defined activity on the design of a context-sensitive expert recommender system; and an evaluation of the process usage by distinct designers on their CSS projects. These studies showed a good acceptance of our proposal and indicated the feasibility of using the process on real projects.