Spinous process implants and associated methods are shown and described. In one aspect, the implant limits the maximum spacing between the spinous processes. In another aspect, a spacer has at least one transverse opening to facilitate tissue in-growth. In another aspect, an implant includes a spacer and separate extensions engageable with the spacer. The spacer is provided in a variety of lengths and superior to inferior surface spacings. In another aspect, an implant includes a spacer and a cerclage element offset from the midline of the spacer in use so that the spacer defines a fulcrum and the cerclage element is operative to impart a moment to the vertebrae about the spacer. In another aspect, instrumentation for inserting the implant is provided. In other aspects, methods for treating spine disease are provided.