The most exciting and difficult challenge facing neuroscientists is to understand the functions of complex neurobiological systems. Computational neuroscience provides a theoretical foundation and set of technological approaches that may enhance our understanding of nervous system function by providing analytical and modeling tools that describe, traverse and integrate different levels of organization, spanning vast temporal and spatial scales. Computational approaches are needed in the study of neuroscience as the requirement for comprehensive analysis and interpretation of complex data sets becomes increasingly important. Collaborations among computer scientists, cognitive scientists, engineers, theoreticians and neuorobiologists are imperative to advance our understanding of the nervous system. Participating Directorates of the National Science Foundation (NSF) and the Institutes of the National Institutes of Health (NIH) (see cover list) plan to support interdisciplinary research in computational neuroscience. Both agencies recognize the need for research that focuses on integrating computational models and methods with neuroscience. This solicitation is designed to encourage new and existing collaborations at this interface.