This paper summarises the what, why and how of inclusive design, and presents key contributions of the 2006–2010 i~design research consortium, the third successive research consortium funded by the Engineering and Physical Sciences Research Council as part of the Extending Quality of Life initiative. Throughout 10 years of i~design research, the overarching goals have been to provide industrial decision makers with mechanisms for understanding the significance of age- and capability-related factors, and to provide the design community with the techniques and guidance required to deliver better products and services for people of all ages and abilities. In this latest period of research, the specific emphasis has been on quantifying design exclusion and enabling designers to work with users.