This paper is a contribution to international learning on the design and functioning of poverty monitoring systems (PMS) in countries with national poverty-reduction strategies (PRS). It is also intended to be useful to the Government of Tanzania and other stakeholders in identifying priorities and approaches for the monitoring of the revised Poverty Reduction Strategy (PRS2). The study was required by its terms of reference to focus on institutional arrangements and not on technical issues, bearing in mind the transformations in national policy processes and the aid relationship that PRSP processes are intended to promote. A realistic treatment was called for, exploring the way monitoring systems actually function, so that genuine lessons can be learned.After an Introduction, the next three sections of the paper a) set out the context; b) describe the elements of Tanzania’s PMS and the main initiative to place these in an overall strategic framework, the Poverty Monitoring Master Plan of 2001; and c) analyse the successes, limitations and challenges associated with this effort. Section 5 draws conclusions that may be of general relevance to the design and evolution of PMSs across countries, and makes some speci?c recommendations for the next period in Tanzania.