Lego is a family business founded in Denmark in 1932 by an artisan carpenter specializing in the manufacture of wooden toys. Over the decades, the group has faced major strategic challenges, which resulted in the toy giant losing its leading position. Several times, the company has reconquered its market through rapid transformations of its business model. True to its values, Lego believes in the creativity of its users and employees and in their ability to define the characteristics of a new product. Lego mobilizes the three key elements of participatory design: the engagement of stakeholders in the design process; the creation of space for physical or digital dialogue to support imagination, creativity, and learning; and allowing divergence of opinion to create an unexpected resource. Transformations of the Lego business model are negotiated. These transformations are discussed in physical and virtual spaces, which allows for differences of opinion and the points of view of heterogeneous actors to be taken into account. Participatory design plays narrative, reflexive, and integrative roles at the same time. It promotes a renewal of efficiency impelled by the successive transformations of Lego's business model.