Exploration activity in lacustrine basins in extensional settings has accelerated in recent years with important discoveries in the South Atlantic Ocean and in East Africa. This presentation reviews reservoir facies in lacustrine-rifts including siliciclastic deposits, mixed siliciclastic-carbonate systems, as well as lacustrine carbonates, as observed in different systems in East Africa. Lacustrine extensional basins are characteristically dominated by siliciclastic deposits, on account of the high-relief on faulted rift margins, and associated deep-basin subsidence. Source rock facies in lake systems are shown to vary dramatically in space and time, based on studies of modern lake basins as well as ancient high-resolution records revealed through scientific drilling. This presentation offers data-intensive perspectives of extant lake basins in both the western and eastern branches of Africa's Great Rift Valley.