This paper describes the monitoring 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 life--are 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.