This study explores a tool used to assess economic development, technological innovation, environmental sustainability and liveability in urban areas. The research employs qualitative and quantitative analysis in the development of an index – the Sustainability–Innovation–Local Economic Development Index (Sustain-LED Index) – that considers macroeconomic and environmental indicators and associated policies implemented in the largest US metropolitan areas. The Sustain-LED Index could broaden the range of tools available to policy-makers for identifying and removing obstacles for improving the quality of life, reducing inequalities and diminishing the degree of pollution in urban areas. It could represent a supporting tool for local entities to design new policies for spurring local economic development and it could be used for designing new urban policies throughout a greater understanding of the economic, social and environmental consequences caused by urbanization.