While academic mainstream urban design theory is caught in a paradigmatic debate concerning normative and positive theories, practice research in the field has focused on the added value of quality design. The purpose is to promote, within the wide range of stakeholders, the concept that quality sells. Most of the research in this area is characterised by a descriptive approach based on best practice examples and lack of empirical evidence. This paper aims to fill this gap by investigating the impact of quality-led design on the value of commercial office properties in the urban core of a UK city. In line with mainstream urban economic theory and suggestions from previous research on the value of urban design, the research underpinning this paper uses Hedonic Price Modelling (HPM) to assess the contribution that high quality urban design makes to office rents. In the quest for quantifying quality a new set of Ñurban scale quality design_ variables is specified and each variable estimated for a unique dataset of property transactions. Another novelty relates to the variables that utilise geospatial analysis with the aim of integrating quantitative methods in urban design research and practice.