The world’s energy scenario is changing rapidly due to the increased focus on addressing challenges posed by energy demand and greenhouse gas (GHG) emissions, especially in the transportation sector. While several approaches and technologies are currently being pursued, the development of cleaner alternative fuels will continue to be an important part of these efforts. In this chapter, we summarize the findings from our recent studies on the combustion and soot characteristics of gasoline–alcohol blends in flame and engine configurations. A three-component toluene primary reference fuel (TPRF), comprising iso-octane, n-heptane, and toluene, is used as a gasoline surrogate, along with one of the three alcohols—methanol, ethanol, and n-butanol. For flame studies, simulations are performed using CHEMKIN-Pro along with detailed gas-phase chemistry and soot models. Results indicate that compared to other components in the mixture, the toluene content and octane sensitivity (S) have a more prominent effect on polycyclic aromatic hydrocarbons (PAHs) and soot formation. Further analysis indicates that the soot inhibiting capability of these alcohols follows the order: methanol > ethanol > n-butanol. Detailed three-dimensional (3D) simulations are also performed for a single-cylinder gasoline compression ignition (GCI) engine to investigate the effects of blending gasoline with biofuels, namely ethanol and n-butanol, on the combustion and soot emissions under low load conditions. It is observed that E45 produces less soot than E20. Due to higher ethanol content and lower toluene content, E45 is found to be less sooting chemically. On the other hand, physical properties have the opposite effect and increase soot emissions for E45. Overall, the chemistry effects dominate resulting in lower soot emissions from E45 than E20. B45 produces significantly more soot than E20 and E45 for all the start-of-injection (SOI) timings considered. Although B45 is less sooting than E20 and E45, its physical properties, mainly HoV and viscosity, mitigate the effects of chemistry and dramatically increase soot emissions. In general, the sooting tendency is found to be strongly coupled with both fuel chemistry and physical properties, with increased susceptibility to physical properties (mainly HoV and viscosity) at advanced SOI conditions.