This experimental work systematically compares the stoichiometric alcohol-gasoline and gasoline-alcohol Dual-Fuel Spark Ignition (DFSI) combustion for engine particle number (PN) reduction and fuel economy improvement using a high compression ratio gasoline engine. Alcohol-gasoline DFSI is based on port fuel injection (PFI) of alcohols with high oxygenated content, high octane number and high latent heat of vaporization and direct injection (DI) of high energy density and high volatility fuel. Alternatively the gasoline-alcohol DFSI is based on PFI of gasoline and DI of alcohols. Two different alcohols were used, including methanol and ethanol for both DFSI strategies. Alcohol mass ratio was varied from 0% to 100% for all DFSI combustion control strategies. Both alcohol-gasoline DFSI and gasoline-alcohol DFSI are effective approaches of using alternative alcohol fuels in practical gasoline engines with the potential to reduce PN and improve fuel economy. With increasing alcohol mass ratio, significant reductions of the PN were observed for both combustion strategies, which could result in a more than 95% reduction of PN compared to the baseline. The magnitudes of the particle number density for the nucleation and the accumulation peaks decreased dramatically for all DFSI combustion control strategies. Gasoline-alcohol DFSI generally showed higher fuel economy improvement and PN reduction compared to the alcohol-gasoline DFSI. (C) 2015 Elsevier Ltd. All rights reserved.