AbstractThe Solar Irradiance Science Team (SIST) #2 (SIST‐2) program is a competitively solicited National Aeronautics and Space Administration (NASA) Earth Science Division science research program providing 3‐year awards beginning in July 2018 to quantify and understand the solar irradiance variability and implications for Earth's climate and atmospheric composition. The purpose for the SIST‐2 program is limited to the accurate specification of the incoming solar irradiance into the Earth system considering the 44‐year satellite data record as well as proxies to which the satellite record can be tied. The SIST‐2 program funded eight research grants to study the variability of the total solar irradiance and solar spectral irradiance and to develop improved space‐based data sets, solar proxies, and variability models of the solar irradiance. The SIST‐2 projects are briefly introduced.