Understanding Design Impact: A new framework for understanding the potential of design and enhancing future professional practice. Design is widely recognised as an important driver for economic performance. However, the value of design has proved resistant to quantification despite research attention since the early 1980s. Correlation between design investment and impact has been demonstrated, but not causation. There is considerable interest from policy and professional bodies in what is described here as ‘Design Impact’. Impact can be measured, for example, by return on investment, increases in profitability or cost reductions. However this only crudely captures the economic impact of a design ingredient. Increasingly, social and environmental impacts are also of interest. The design profession sees the potential for better articulation of design impact as a means to increase their influence. The context has been explored through a series of descriptive and prescriptive studies including analysis of 45 DBA Design Effectiveness Award case studies, 304 undergraduate design projects from two institutions over a three year period together with interviews and workshops with senior design professionals and design academics. A new Understanding Design Impact framework is the overall outcome and contribution to knowledge from the work. This bridges between theory and practice and is a powerful basis for placing consideration of design impact at the heart of design activity. A design impact ontology has been developed as a robust foundation to the framework which resolves issues with underlying concepts. An initial version of this ontology is published in The Design Journal and is claimed as a supporting contribution to new knowledge. So too are new ontological classifications of factors which have considerable influence on design impact: Design Influences and Authority and Motivation and Path. These provide fresh perspectives and are worthy of further research consideration. A number of routes are identified for the further development and dissemination of the framework.