The impact of design development on the overall success of a business positions the area as an important performance improvement opportunity. However, design development is exemplified by novelty and non-repeatability, characteristics which provide particular challenges in the definition, measurement and management of performance with a view to improvement. Design Performance scrutinizes the support for improvement in design development provided by research into general business processes and design in particular. The nature of design development in industrial practice is explored and requirements for its modelling and analysis are highlighted. The methods employed encapsulate a formalism composed of three models: E2 formalises and relates the effectiveness and efficiency of a design; Design Activity Management distinguishes design and design management in terms of the knowledge processed in each activity; Performance Measurement and Management describes how these activities relate to each other within the milieu of measurement and management. A computer-based tool that enables the industrial implementation of the PERFORM approach (analysing the influence of resources on an aspect of design performance) and the identification of appropriate means of design improvement is presented. Design Performance illustrates its methodological principles with worked examples and details of industrial practice making it suitable for an academic teaching and research readership as well as for commercial designers and managers.The impact of design development on the overall success of a business positions the area as an important performance improvement opportunity. However, design development is exemplified by novelty and non-repeatability, characteristics which provide particular challenges in the definition, measurement and management of performance with a view to improvement. Design Performance scrutinizes the support for improvement in design development provided by research into general business processes and design in particular. The nature of design development in industrial practice is explored and requirements for its modelling and analysis are highlighted. The methods employed encapsulate a formalism composed of three models: E2 formalises and relates the effectiveness and efficiency of a design; Design Activity Management distinguishes design and design management in terms of the knowledge processed in each activity; Performance Measurement and Management describes how these activities relate to each other within the milieu of measurement and management. A computer-based tool that enables the industrial implementation of the PERFORM approach (analysing the influence of resources on an aspect of design performance) and the identification of appropriate means of design improvement is presented. Design Performance illustrates its methodological principles with worked examples and details of industrial practice making it suitable for an academic teaching and research readership as well as for commercial designers and managers.