http://www.ub.es/geocrit/-xcol/73.htmInternational audienceTwo crossed experiences – one of a geographer in India and Brazil, another from an anthropologist in French Guyana and Brazil - are here put in perspective to initiate a theoretical and methodological reflection around the role of space in the field investigation, as a context of inquiry as much as resource mobilized by actors. In fact, this contribution deals with change in a double dimension: in the capacity of the actors, involved in individual or collective strategies to deal with their own future, to initiate alterations and in their daily space, Rio de Janeiro metropolis, whose political space is submitted to the necessity to generate dynamic that can be evaluated in the perspective of the "urban sustainability". The observation of the practices of actors acting between formal and informal spheres, marked for their social and space mobility, and for their flexibility of performance and institutionalization, brought us to proceed to the definition of an interdisciplinary glance, this permitting to locate them in the core of the sustainable dynamics of Rio De Janeiro metropolis. In the construction of this look, between theory, methodology and extension, the role of the two individual research itineraries is central, as much as the understanding of their meeting that happened in the scope of the research group FACI (Favela and Citizenship) of the Federal University of Rio De Janeiro, as it allows us, since 2005, to develop theoretical empirical research and reflection around these changes of paradigm