This paper comments on the current state of knowledge in the field of hydrogeology and claims that fundamental understandings must be developed if creative research is to have maximum impact. Problems of great importance to society include water development and quality, waste disposal, and global cycling of resources. These problems cannot be addressed effectively unless significant advances are made in understanding of a range of challenging scientific issues including fundamental physics, the importance of scale, modeling, and chemical and biological processes. Meaningful advances in hydrogeologic research will require an increased emphasis on fundamental understanding, interdisciplinary approaches, educational reforms, and the attraction of excellent researchers to the field.