A process is disclosed for converting a light hydrocarbon feedstock that contains a mixture of linear and branched olefins to ether-rich high octane gasoline streams that include tertiary alkyl and isoalkyl ethers such as MTBE, TAME, methyl isopropyl ether (MIPE), and methyl sec-butylether (MSBE). The process involves initially etherifying the tertiary olefins with a lower alcohol in the presence of an ion exchange resin catalyst, and then etherifying the linear olefins in the presence of a zeolite catalyst, such as zeolite beta. The unreacted olefins from the etherification reactions are converted to gasoline boiling range hydrocarbons by oligomerization with a zeolite catalyst, such as ZSM-5.