Abstract:   Scenarios in HCI are widely used and discussed as written or visual narratives. In this paper, we discuss fruitful conditions for the creation and performance of scenarios particularly for the concept design of mixed realities or wireless devices. Designers are attempting new ways of engaging people in design and experiencing ideas in early design phases. Examples range from exploring scenarios using mock-ups or Wizard-of-Oz techniques, to testing scenarios with prototypes. In our design projects, scenarios were created and performed with participants following them in their daily activities. Discussing these sessions, which we called SPES (Situated and Participative Enactment of Scenarios), we highlight as promising conditions to create scenarios: the everyday life as a stage and the opportunity for participants to exercise reflection-in-action.