A memory includes a selection circuit and a write assist circuit. The selection circuit has a first input, a second input coupled to a first power supply voltage terminal, an output coupled to a power supply terminal of each of a plurality of memory cells, and a control input for receiving a write assist control signal. The write assist circuit is coupled to the first input of the selection circuit for reducing a voltage at the power supply terminal of each of the plurality of memory cells during a write operation and in response to an asserted write assist enable signal. The write assist circuit comprises a P-channel transistor and a bias voltage generator. The P-channel transistor is for reducing the voltage at the power supply terminal of each of the plurality of memory cells during the write operation. The bias voltage generator is for providing a variable bias voltage to the P-channel transistor.