Numerous recent studies have demonstrated the significant opportunity to enhance vapor-compression cycle COP by integration of a two-phase ejector, especially for transcritical CO2 cycles. However, this significant improvement in performance relies on proper control of the ejector cycle. This paper investigates different methods for controlling the high-side pressure of a transcritical CO2 ejector cycle. The use of an ejector with an adjustable motive nozzle throat area as well as a simple expansion valve in series or parallel with a fixed-geometry ejector to actively control high-side pressure are investigated over a range of conditions. Additionally, proper control of evaporator flow rate, which is often overlooked in studies addressing ejector cycle control, for different conditions is also investigated. Ejector cycle control is investigated over a range of capacities and ambient temperatures in order to see the performance penalties to a transcritical CO2 ejector cycle when it is not controlled properly.