This document is focused on the structural features of rivers, on geomorphological and hydrological processes, and on river continuity. It provides guidance on the features and processes to be taken into account when characterizing and assessing the hydromorphology of rivers. It is based on methods developed, tested, and compared in Europe. Its main aim is to improve the comparability of hydromorphological assessment methods, data processing and interpretation. Although it has particular importance for the WFD by providing guidance on assessing hydromorphological quality, it has considerably wider scope for other applications. In addition, while recognizing the important influence of hydromorphology on plant and animal ecology, no attempt is made to provide guidance in this area, but where the biota have an important influence on hydromorphology these influences are included. NOTE A case study illustrating the application of this standard is given in Gurnell and Grabowski[1].