We developed an Earth System Model (ESM) aerosol-cloud diagnostics package (ESMAC Diags) to facilitate the routine evaluation of aerosols, clouds and aerosol-cloud interactions simulated by the Department of Energy’s (DOE) Energy Exascale Earth System Model (E3SM). The diagnostics package focuses on comparing simulated aerosol and cloud properties with in-situ and remote-sensing measurements from aircraft, ship, surface and satellite platforms. The diagnostics currently covers six field campaigns in four geographical regions: Eastern North Atlantic (ENA), Central U.S. (CUS), Northeastern Pacific (NEP) and Southern Ocean (SO). These regions produce frequent liquid or mixed-phase clouds with extensive measurements available from the Atmospheric Radiation Measurement (ARM) program and other agencies. An “aircraft simulator” is used to extract aerosol and meteorological model variables along flight paths that vary in space and time. Similarly, the aircraft simulator is applied to ship tracks in which the altitude remains fixed at sea level. ESMAC Diags includes various types of single-variable and multi-variable relations diagnostics, such as percentiles, histograms, joint histograms and heatmaps, to evaluate aerosols, clouds and aerosol-cloud interactions. We will present an overall introduction of ESMAC Diags, show examples on how E3SM represents aerosols, clouds and aerosol-cloud interactions in different climate regimes, and discuss any improvements from E3SMv1 to E3SMv2. Mechanisms and factors that contribute to the model bias will be diagnosed and discussed.