Expandable interspinous process spacer

An expandable interspinous process spacer implant for insertion and/or implantation between a spinous process of a superior vertebral body and a spinous process of an inferior vertebral body, the implant comprising multiple pairs of legs joined in a scissor-like fashion and pivotally coupled to each other by one or more pins, where each leg has multiple slots along its longitudinal axis. The implant further may include a pair of bearing surfaces coupled between the legs via cross pins and a first plate and second plate each of which is coupled to a pair of roller pins disposed between a pair of slots on the legs where rotation of a fastener in the fastener holes of the first and second plate results in the first plate and the second plate being drawn toward each other causing the expansion of the height of the implant.