Architect John Habraken visited the School of Architecture in Barcelona (ETSAB-UPC) in April 2008, from the 18th to the 25th, and directed a workshop as part of the Master's program Laboratorio de la vivienda del siglo XXI sponsored by the Fundaci Politcnica de Catalunya. He was assisted by the Puerto Rican architect Andrs Mignucci. For the fourth edition of the Master, Habraken's visit constitutes a milestone. The key concepts put forward by the Laboratorio coincide with Supports theory: flexibility in mass housing, user participation, and appropriate use of technologies as applied to construction.