This paper presents a brief overview and technical highlights of the research efforts and studies on rotary engines over the last several years at the NASA Lewis Research Center. The review covers the test results obtained from turbocharged rotary engines and preliminary results from a high performance single-rotor engine. Combustion modeling studies of the rotary engine and the use of a Laser Doppler Velocimeter to confirm the studies are discussed. An in-house program in which a turbocharged rotary engine was installed in a Cessna Skymaster for ground test studies is also covered. Details are presented on single-rotor stratified-charge rotary engine research efforts, both in-house and on contract.