This paper reflects on the findings of an impact assessment of slum upgrading programmes in three cities in India. The study was commissioned by the donor that had funded them, the UK Government’s Department for International Development, to consider their effectiveness in reducing poverty. The paper documents the approach taken, including formal survey work and extensive consultation with households in 12 slums, and presents the findings. These highlight the many dimensions of deprivation faced by slum dwellers. They also point to the relative success of upgrading projects in providing basic infrastructure (and its direct and indirect impacts). The paper also discusses the difficulties in drawing simple policy recommendations and the often unexpected (and indirect) ways in which studies such as these influence international donors, including those that commission them.