The South America Affinity Group (SAAG) was established in early 2019 by the National Center for Atmospheric Research (NCAR) Water Systems Program as a community effort focused on improving hydroclimate science over South America. SAAG supports large research efforts such as the ANDEX Regional Hydroclimate Program (Espinoza et al. 2020) as well as individual research groups. The group started with a dozen members and quickly grew to over 100 participants from more than 10 countries. For the past four years, the SAAG has been meeting online every two weeks and has organized sessions at international conferences such as the American Geophysical Union Fall Meeting and the Convection-Permitting Climate Workshop (Prein et al. 2022). At the core of the SAAG effort are two multidecadal convection-permitting (CP) model simulations with 4-km grid spacing for historical and future climates over the South American continent. Additionally, a major observational data collection effort has been undertaken, including in situ station data from South American meteorological and water services, gridded products, satellite-based observations, and field campaign data (NCAR 2023a). This article discusses the research needs and scientific goals that drive this community of scientists with diverse backgrounds and interests.