Parametric studies of direct injection (DI) compression ignition (CI) engine combustion fueled with gasoline are presented. A multi-dimensional CFD code, KIVA-ERC-Chemkin, coupled with improved sub-models and the Chemkin library, was employed. The oxidation chemistry of the fuel was calculated using a reduced mechanism for primary reference fuel combustion. The results show that high pressure DI gasoline engine combustion and emissions are successfully predicted and are in good agreement with available experimental measurements under various operating conditions. It is seen that gasoline has a much longer ignition delay than diesel fuel for the same combustion phasing; thus, oxides of nitrogen (NOx) and particulate emissions are significantly reduced compared to corresponding diesel-fueled cases. The results also suggest possible methods for expanding the operating conditions of DI gasoline compression ignition (CI) combustion. This indicates that the application of gasoline fueling to compression ignition engines is likely to lead to low-emission engine concepts.