A device for treating spinal stenosis having an implant body structure sized and configured to be positioned between the spinous processes of two adjacent vertebrae. The device may have a body portion having a first end portion, a second end portion and a sleeve between the first and second end portions. The device may also have at least two retainers positioned in and extendable from the body portion. A mechanism positioned within the body portion may be used to move the retainers between a retracted position and a deployed position. When the retainers are in the deployed position, the retainers may be positioned around the spinous process of at least one of two adjacent vertebrae. A plurality of installation tools may be used to install the device.