Attribution is the establishment of a causal link between (parts of) an observed change and a specific intervention. Attribution is a key requirement of any monitoring and results measurement (MRM) and evaluation activity. Donors require programmes to show whether, and to what extent, the results they are reporting are caused by their interventions. There are many opinions on how to attribute changes to interventions. This is particularly true for interventions in complex systems such as markets. Some practitioners and authors say that it’s not possible to attribute change to market system interventions, while others say that there are well-established quantitative methods of doing so. This paper sheds light on the current theoretical/academic and practitioner understanding of attribution and causality. It then suggests a typology for attribution to create a better understanding of when one method is more appropriate than another.