Describes and evaluates a six-moment aerosol microphysical module, 6M, designed for implementation in atmospheric chemical transport models (CTMs). The module 6M is based upon the quadrature method of moments (QMOM) (McGraw, 1997) and the multiple isomomental distribution aerosol surrogate (MIDAS) method (Wright, 2000). The module 6M evolves the lowest six radial moments of H2SO4-H2O aerosols for a comprehensive set of dynamical processes including the formation of new particles via binary H2SO4-H2O nucleation, condensational growth, coagulation, evolution due to cloud processing, size-resolved dry deposition, and water uptake and release with changing relative humidity. Performance of the moment-based aerosol evolution is examined and evaluated by comparison with results obtained using a high-resolution discrete model of the particle dynamics for a range of conditions representative of the boundary layer and lower troposphere