The International Global Atmospheric Chemistry (IGAC) Project, formalized in 1990, seeks to progress atmospheric chemistry towards a sustainable world by advancing knowledge, fostering community, building capacity, and engaging society. Most known for its international biennial science conferences, IGAC also has ten community-driven activities, centered around scientific questions that need global collaboration to answer (e.g., tropospheric ozone, emissions, biomass burning uncertainties) and eight regional working groups led by regional scientists in areas where atmospheric chemistry has traditionally been underdeveloped. IGAC is a large international community, with 1500 people on the mailing list and 300-700 attendees to each conference. The project is led by a rotating 16-20 member international scientific steering committee (SSC) and has recently added an early career researcher SSC. IGAC is a Global Research Network (GRN) under the umbrella of Future Earth, a sustainability science organization. We welcome contributions from members at all times and strive to evolve with the needs of the community.