Despite the proposed advantages of systems accident analysis (SAA) methods for understanding incident causation, they have not been widely adopted by practitioners. The aim of this study was to evaluate the criterion-referenced validity of an SAA method embedded within an incident reporting software tool. Thirteen practitioners used the tool to collect and analyse incident data within their organisation. The incident data were then analysed by researchers experienced in using the SAA method. Overall, there were low levels of agreement between participants and researchers regarding the identification and classification of factors and relationships. The findings indicate the systems thinking principles underpinning the SAA method may have been ‘lost in translation’, in that participants often identified only one or two factors and showed a poor understanding of how to identify relationships between factors. The methodological developments required to ensure that practitioners can validly apply the SAA method are discussed.