With the ongoing sprawl of residential and work places, in addition to those of consumption and leisure, as well as an increasing autonomy of household members in car-dependent lifestyles, we are witnessing the generalized and customized use of large fractions of metropolitan areas. Our qualitative surveys conducted over the last ten years confirm that residents from central and peripheral areas have territorial representations of the metropolitan area that are diversified and partial with inconsistent and fuzzy boundaries. Identifying urban policies and planning strategies that protect ecosystems and cultural landscapes, reduce urban sprawl, lower car dependency, and maintain shops and services accessible to less mobile citizens has become a priority for governments. If implementing sustainable policies and projects on these extended territories is a significant challenge, elaborating them with the population is even more so. Can participatory processes be conducted with citizens of such large territories? This is the question the Interdisciplinary Research Group on the Suburbs (GIRBa) is attempting to answer.How can the 750,000 inhabitants of the Quebec City metropolitan area, living in twenty-eight towns and villages spread over 3500 km2, be mobilized around a collective sustainable metropolitan project? The participatory process put forward calls for the use of web-based information and communication technologies to inform, consult, and aid in the decision-making process. The three-step process relies on the Internet, using on-line consultation, participatory geographic information systems (PPGIS) and social media. The first step, completed in June 2011, consisted of an Internet survey opened to all Quebec metropolitan area residents to identify various citizen profiles with regard to personal and family characteristics, lifestyles, and understand their mobility patterns and residential behaviors. Over 2300 citizens answered the three-module questionnaire. These profiles will be used in Fall 2012 to inform the development of sustainable metropolitan scenarios with a limited group of local experts, decision makers and citizens in the context of an urban design studio. This studio will be a first opportunity to test on a limited group of actors the prototype of a web interface developed in geomatics. Participants will use an interface such as Google Map to tag their comments on the proposals and interact with the team through social media. The next step will consist of testing the scenarios through an internet consultation open to the 1000 Internet survey participants who volunteered, using improved versions of the PPGIS and social media procedures. The last step, planned for 2014, consists of a collaborative process bringing face-to-face key experts, decision makers and citizens to finalize the consensually defined Quebec sustainable metropolitan plan. This communication presents the entire process as well as its advancement as of June 2012.