Mathematical Knowledge Management (MKM) is a new interdisciplinary field of research in the intersection of mathematics, computer science, library science, and scientific publishing. Its objective is to develop new and better ways of managing mathematical knowledge using sophisticated software tools. Its grand challenge is to create a universal digital mathematics library (UDML), accessible via the World-Wide Web, that contains essentially all mathematical knowledge (intended for the public). The challenges facing MKM are daunting, but a UDML, even just partially constructed, would transform how mathematics is learned and practiced.