In the past decade, NASA’s Kepler mission has revealed that most stars host planets, many of them are Earth-sized. From Kepler, observations indicate that the Milky Way may be home to billions of Earth-sized planets orbiting in the habitable zone of their host stars. With this knowledge, the possibility of finding life beyond Earth looms larger on the horizon. NExSS grew from this realization and the recognition that a synthesized approach that draws on expertise from many fields is required to maximize the information from these discoveries and accelerate future progress. The key to understanding exoplanet habitability is understanding how biology interacts with the atmosphere, geology, oceans, and interior of a planet, and how these interactions are affected by the host star. This “systems science” approach will help scientists better understand how to look for life on exoplanets. NExSS provides framework for a collaboration among the four science communities supported by NASA’s Science Mission Directorate: Earth scientists, planetary scientists, heliophysicists, and astrophysicists.