The main features of the global modeling of secondary organic aerosol (SOA) based on actual knowledge are described. Areas where significant progress in our understanding of SOA formation and fate has been made over the last 2 years, are outlined. The implications of these new findings for the global modeling of SOA are discussed. The importance of biogenic versus anthropogenic SOA is discussed as well as potentially related feedback mechanisms between the biosphere/atmosphere and climate. SOA is shown to be the major component of organic aerosol (OA) exceeding by 25% the primary emitted OA on a global annual basis. Model deficiencies are evaluated via comparison with available observational data. Finally, areas where future research is critical for an enhanced understanding of organic aerosol occurrence and fate in the atmosphere are highlighted.