The IAHS Decade on Predictions in Ungauged Basins (PUB) is an initiative of the International Association of Hydrological Sciences (IAHS) aimed at formulating and implementing appropriate science programs to engage and energize the scientific community, in a coordinated manner, towards achieving major advances in the capacity to make reliable predictions in ungauged basins. Now two years into the effort, PUB participants have defined a set of community science questions in the hydrological sciences with broad consensus and community buy-in. As the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) begins its community science question-building effort, there is much that can be learned from the PUB experience?both good and bad. The PUB example provides a potential template for the USA CUAHSI community. This proposal requests NSF funding to support the preparation and implementation of a four-day workshop to catalyse the identification of community science questions by the USA hydrologic community. Workshop goals are: 1) introduce PUB science processes to the USA hydrological community; 2) explore the utility of six major PUB science themes as a potential template for USA community science questions; 3) critically discuss the open questions in hydrology as they pertain to the establishment of hydrologic observatories; and, 4) spark dialogue among participants to identify the most promising avenues for the efficient development of community science questions. The workshop will be convened by leaders of the USA?s hydrologic science community and feature presentations by over 30 experts widely recognized in their fields. The workshop will be among the first to be conducted in association with the newly established National Center for Hydrologic Synthesis at the University of California, Berkeley. The workshop will employ the AGU Chapman Conference style that features substantial discussion ?space? to facilitate a high level of thoughtful participant interactions with speakers and each other. The workshop?s intellectual merit derives from the clear need for USA hydrologists to share experiences, debate approaches, and reach consensus on a new science plan that embodies a response to the growing demand for multidisciplinary approaches to advance the science of hydrology. The workshop?s nationally- and internationally-recognized speakers will deliver compelling content over a broad range of hydrologic topics to participants?all within a format designed to challenge assumptions, optimize debate, and inform agreement. The broader implications of the workshop reach to society?s ability to access, understand, and act upon improved prediction capacities resulting from a new, more holistic, and effective orchestration of hydrologic inquiry. The workshop will help define a new trajectory of research that will allow water resources decisions to be made with greater resolution, in a more timely manner, and with substantially more confidence.