This chapter focuses on the preliminary design stage for ambient socio-technical systems that are not designed for a specific application, but a more general application that is described by one or more scenarios. The aim here is partly to examine tests led in the workshop on ambient systems, which have been undertaken at ETIA (Ecole Thématique Intelligence Ambiante). The chapter traces the experimentation of initial forays into real-life scenario-based ambient systems in the form of the Ambient Campus. Next, the chapter details the major challenges in computing research highlighted in the workshop. These scientific issues are described in terms of Amilab's major aspects. The major scientific challenges raised such as acceptability, respect for private life, reliability, openness, and interoperability, reflect the complexity of designing these systems. In addition, these challenges characterize future ambient systems.