The Gipuzkoa branch of the Basque and Navarre College of Architects organized, within the MUGAK Architecture Biennial, the exposition “The Transgenerational House.” It took place in a pavilion specially built for the purpose in a public space in the city of San Sebastian (Spain). In it, both a conventional furnished home and an alternative one, with the possibility of allowing free spatial divisions and furnishing distribution, were recreated. Some architectural teams showed their experiences on housing. A set of components with a color code was developed to link the two homes and the work of the architects. The pavilion was opened to the public, which had access to the contained information in a partially directed way and participated answering to posed specific questions. Additionally, 10 structured workshops with different collectives were organized, making specific proposals on the alternative home. The overall exposition is shown, reflecting on the advantages and limitations of citizen participation as an instrument of sustainable development.