Models are ubiquitous tools for advancing science; they allow scientists to deal with the complexity of the natural-human environment, with the interdisciplinarity of national environmental problems, and with the novelty and sheer quantity of data from observatories such as NEON. Models will play a central and essential role in NEON from the first steps of planning to the final stages of synthesis and forecasting. Models are essential for selecting sensors and designing optimal plans for sensor array deployment, data assimilation, error analysis, quality assurance, interpolation to fill the inevitable gaps in data, and for forecasting trends. Models will be required by NEON for spatial projections within regions and across the nation as a whole, and for high-level synthesis within and across the major questions that organize NEON research. Finally, models will facilitate outreach by NEON to stakeholders including decision makers at the local, regional and national scale.