For over 50 years the International Atomic Energy Agency (IAEA) has hosted its quadrennial International Symposium on Isotope Hydrology. This Symposium provides a unique forum to review the state of isotope hydrology, to showcase new and practical isotope applications, and to highlight emerging areas of research leading to the advancement of the hydrological sciences. The field of isotope hydrology has been a longstanding and key contributor to our scientific understanding of global and regional water cycles, and plays a key role in water security by aiding better water resource assessments and management, evaluating surface and ground water pollution issues, and as an archive of long term changes in the Earth’s climate. Isotope hydrology has more recently emerged as a foundational discipline that enabled entirely new areas of applied research in ecology, wildlife forensics, and in global food traceability. The 2015 Isotope Hydrology Symposium is the 14th meeting. It will be held at the IAEA Headquarters in Vienna, Austria, from 11-15 May 2015. The symposium will facilitate the exchange of information and knowledge among water and environment professionals from developed and developing member state countries.