Hydrology in Scotland has emerged as a diverse and maturing discipline in recent years following its origins in engineering and the environmental sciences. Despite significant progress in understanding the physical, chemical and biological aspects of the hydrological cycle in Scotland, hydrologists face a number of significant challenges. These include: improved basic process understanding and modelling of catchment functioning; increased understanding of climatic variability and change; the collection of more extensive and well-integrated data sets; improved understanding of the role of hydrology in maintaining good ecological status in managed rivers; and a rapidly evolving policy agenda both within Scotland and the EU. So far, the response of the scientific community to these challenges has been encouraging. However, it is concluded that in the future, hydrologists need to be increasingly engaged in interdisciplinary research projects and communicate better with environmental planners and various stakeholder groups if the discipline is going to make its full contribution to sustainable water resource management in Scotland.