The Nexus for Exoplanet System Science (NExSS) is a NASA Research Coordination Network (RCN) dedicated to the study of planetary habitability. The goals of NExSS are to investigate the diversity of exoplanets and to learn how their history, geology, and climate interact to create the conditions for life. NExSS investigators also strive to put planets into an architectural context, as solar systems built over the eons through dynamical processes are sculpted by their stars. Based on our understanding of our own solar system and habitable planet Earth, researchers in the network aim to identify where habitable niches are most likely to occur, and which planets are most likely to be habitable. Leveraging current NASA investments in research and missions, NExSS will accelerate the discovery and characterization of other potentially life-bearing worlds in the galaxy, using a systems science approach. NExSS coordinates exoplanet research that involves the expertise of all four of the Science Mission Directorate (SMD)’s Divisions (Astrophysics, Earth Science, Heliophysics, Planetary Science). Funding for the research performed by members of NExSS is provided by the Planetary Science and Astrophysics Divisions; funding for the administration of the RCN is provided by the Planetary Science Division.