The key aim of classification in Para sport is to try and ensure that competitors are grouped so that they compete against others with impairments that cause a similar level of activity limitation within a specific sport. This synthesis aimed to identify existing, valid, and reliable, impairment assessment tools to measure eligible impairments that influence an individual's ability to compete at Para dressage. A multi-stage approach was employed, where a systematic search of professional databases of impairment assessment tools first identified 35 tools for Para dressage. Then, a search strategy was developed, based on these 35 tools, and 305 scientific articles were identified from academic databases up to September 2021. From here, impairment assessment tools were evaluated and refined in a twostage process using known performance determinants for Para dressage and then an assessment of their reliability, validity and practical usability. This resulted in the selection of impairment assessment tools, which included measures of muscle tone, strength, coordination, sitting balance, and trunk function. From this synthesis, we present a novel process by which impairment assessment tools were selected, refined, and critically examined using knowledge of performance determinants for dressage, the views and experiences of stakeholders, and reliability and validity of tools. The processes described here could be applied to the development of evidence-based classification systems across a range of Para sports.