A process for converting an olefinic gasoline to a higher octane value gasoline comprises the steps of subjecting the feed gasoline, or a fraction thereof, to olefin disproportionation in the presence of added ethylene to convert some of the heavier olefins to lighter olefins, disproportionating propylene produced by the first step to ethylene and butenes, alkylating the butenes with isobutane, catalytically reforming a C5+ fraction from the first step, and recombining the alkylate and reformate with unconverted gasoline fractions to form the higher octane gasoline.