This paper describes the Participatory Impact Assessment and Learning Approach (PIALA) which was developed and piloted by IFAD. The approach aims to produce rigorous qualitative and quantitative evidence that can be used not only to identify and assess the impacts of development projects, but also to promote learning and improved understanding of the associated processes and pathways of socio-economic change. Illustrated with cases from Viet Nam and Ghana, the paper assesses the value of the approach for collaborative learning and reporting for IFAD’s country programming and global policy engagement, as well as for the wider development community.