In 2020/2021, Plan Eval delivered a large-scale impact evaluation of the PROSAMIM III re-settlement and slum upgrade programme. The evaluation was based on (i) a longitudinal study with resettled families, comparing the situation before and after the move; (ii) an impact assessment with a treatment group and a control group; (iii) a stakeholder satisfaction survey; and (iv) document review, focus groups and interviews with implementing partners. The evaluation was used to improve the programme and secure donor funding for its subsequent phase.