This paper describes the monitorin g system of the urban quality of life developed by the Porto City Council, a new tool being used to support urban planning and management. The two components of this system -a quantitative approach based on statistical indicators and a qualitative analysis based on the citizens' perceptions of the conditions of lifeare presented. The strengths and weaknesses of these two approaches adopted in the project are reviewed. It is argued that, in order to achieve a deeper understanding and more effective measurement of urban quality of life, both kinds of measurements are useful and complement each other.