Abstract: We need more, and better, fish pass performance data in order to inform and improve on our current fish pass designs. Relatively few fish pass construction projects currently budget for accompanying monitoring programmes and those monitoring studies that do take place vary widely in terms of the terminology and methodology used. This variability of data and lack of transferable knowledge is a major constraint on the development of fish pass design internationally. In order to maximise the benefit from expensive monitoring studies, the results need to be pooled and compared, which is not possible when studies measure different efficiency and effectiveness metrics. A standardised approach which defines the terminology, metrics and provides a framework for experimental design to achieve robust measurement of these metrics would help to address this issue. Standardising fish pass evaluation would help to improve the accuracy of efficiency and effectiveness estimates and provide information in a transferable form that can then be used to compare across studies and fish pass types, ultimately improving fish pass designs. Methodological standards in Europe are developed through the European Committee for Standardisation (CEN); typically taking 3 years to reach publication. A ‘Fish Pass Evaluation’ New Work Item proposal has been submitted to CEN with the UK’s Environment Agency leading the project. This presentation will provide an outline of the CEN Standards process, the vision for what a fish pass monitoring standard could contain and an update on progress. It is hoped that this will stimulate discussion and involvement from fish passage scientists, both within and beyond the 33 Member States, which is critical to the successful development, implementation and potential exportation of a European Standard, thereby increasing the pool of comparable data.