With increasing efforts being made to introduce systematic interventions for encouraging abandonment of female genital cutting (FGC) comes the need to better understand how such interventions work and what effects they have. Many interventions are based on theoretical models of behaviour change and so studies to evaluate them should develop indicators appropriate to the type of behaviour change anticipated. Systematic evaluations need also to use some form of quasi-experimental design to be able to attribute change to the intervention and not to any ‘natural’ change in FGC behaviour or other activities that may be concurrent. A sustained change in the prevalence of FGC is the ultimate indicator and there are several ways this can be measured, although with many limitations given the intimate nature of the practice. Moreover, appropriate sample sizes must be calculated and used to be able to draw valid conclusions. Many of those implementing FGC interventions are not familiar with such basic research principles and so there is an urgent need to ensure that projects are well designed so that valid conclusions concerning their effectiveness can be drawn.