A process evaluation provides critical information that can inform the design and implementation of a programme. This study sought to provide examples of how to operationalize a process evaluation of an effective programme (Skills for Preventing Injury in Youth). A comprehensive definition of process evaluation was used which included assessing dose, adherence, quality of process, participant responsiveness and programme differentiation. Dose was assessed through teacher and student ratings as well as independent observations. Reports from an observer were used to assess adherence to programme objectives, the quality of process including interactive delivery and programme differentiation. Participant responsiveness was assessed quantitatively and qualitatively with students providing greater depth to the findings. Findings regarding dose varied and suggested different sources of reports provided supplementary information. The findings also suggested that independent observations are an important tool for process evaluation and identified challenges for programme designers regarding interactive material. Overall, the research indicated that a comprehensive definition of process evaluation could be operationalized and provided an understanding of an application of a process evaluation to an injury prevention programme. Continued development of process evaluations will enable a better understanding of the conduct of interventions and maximize the likely effect of such interventions.