An implantable spacer for placement between adjacent spinous processes is provided. The spacer includes a body and a wing rotatable connected to the body. The wing includes two U-shaped configurations that together define a substantially H-shaped configuration for retaining the spacer between adjacent spinous processes. An actuator assembly is connected to the body and to the wing with the proximal end of the spacer being connectable to a removable driver that is configured to engage the actuator assembly. While connected to the spacer, the driver is rotatable in one direction to deploy the wing from an undeployed to a deployed configuration and in an opposite direction to undeploy the wing. In the deployed configuration, the spacer acts as a space holder opening up the area of the spinal canal, maintaining foraminal height, reducing stress on the facet joints and relieving pain for the patient.