Children are a key target of handwashing interventions as washing hands reduces the spread of disease and reliance on antibiotics. While there is guidance for evaluating handwashing with adults in other settings, this is lacking for children in schools. An integrative review of sixty-five studies where handwashing was measured in schools was conducted to establish which indicative measures (what is measured to evaluate the processes and/or impacts of, handwashing) and measurement tools (data collection instruments) have been applied to evaluate handwashing in schools, and under what circumstances. Further analysis highlighted different challenges when seeking to apply such measures and tools in schools, as opposed to other settings. It was concluded that indicative measures and measurement tools need to be appropriate to the organisational setting, the study participants, and research objectives. A summative analysis of relevant considerations is presented.