An agenda for land-surface hydrology research is proposed to open the debate for more comprehensive prioritization of science and application activities in the hydrologic sciences. A set of science questions are posed and the observational requirements to achieve substantial progress are identified. In this context, the proposal to initiate the 2nd International Hydrologic Decade (IHD) is put forth. The benefits of this initiative for enhanced scientific understanding and improved capability in meeting societal needs are also identified.