This article is part of a project that aims to design an innovative home-assistance in order to allow seniors to benefit from medical surveillance at home as well as to have access to new opportunities for communications and information with the “outside world”. This analysis takes place while the system does not yet exist, except the specification of the functions. This paper is thus directly related to Prospective Ergonomics and allows a reflection on the methods to be used in such a context. To this end, we describe various methods that we consider as particularly relevant and we present previous studies that are useful for this design project. Based on these analyses, we propose a suitable methodology for the considered population in order to obtain information elements to build strong assumptions about users’ needs and to derive recommendations for designing the new technological environment. Especially, we argue the utility of the use of methods related to Participatory Design and we propose to involve future users (called “participants”) in the assessments of designers’ proposals as well as in the generation of new proposals. We also suggest to stimulate participants to bring out their needs and to propose creative ideas during meetings. In accordance with these postulates and the various methods and studies that are described, we finally present recommendations for our project about an innovative home-assistance for seniors.