Ethanol is one of the most suitable alternative fuel for spark-ignition (SI) engines. Its properties such as the higher evaporation heat and octane number as well as the larger oxygen content allow to obtain positive effect on engine performance and on particle formation and emissions. This paper aims to analyze the effect of different methods of ethanol fueling on in-cylinder soot formation and exhaust emissions in a small displacement spark ignition engine. The engine was fueled with gasoline and ethanol. In particular, the ethanol was both blended with gasoline (E30) and dual fueled (EDF). In this latter case, ethanol was direct injected and gasoline was injected into the intake duct. For both the injection configurations, the same percentage of ethanol was supplied: 30%v/v ethanol in gasoline. The GPFI and GDI configurations were also performed as base case. The experimental investigation was carried out in 4-stroke small single cylinder engine. The measurements were carried out at 2000 and 4000 rpm under full load condition. Optical technique based on 2D-digital imaging was used to follow the combustion process. Two-color pyrometry was applied to assess the in-cylinder soot formation. Particle emissions were measured at the exhaust by means of a smoke meter. Particle size distribution function was measured in the range from 5.6 to 560 nm by means of an Engine Exhaust Particle Sizer (EEPS). For E30 the in- cylinder soot formation and emissions are larger than for EDF because of the different contribution of gasoline, which leads to the formation of wide diffusive flame where soot formation is promoted. In EDF the better evaporation and mixing of gasoline, typical of PFI configuration, results in reduced diffusive flame and lower particle emissions.