A method for implanting an interspinous process spacer includes deforming a spacer from an extended configuration to a collapsed configuration. The spacer has a first pair of resiliently deformable arms extending from a central section of the spacer and when the spacer is deformed into the collapsed configuration, the first pair of arms moves toward each other. When in the collapsed configuration, the spacer is advanced into a guide tube such that the first pair of arms is constrained only by the guide tube. The guide tube is positioned proximate a pair of adjacent spinous processes and then the spacer is removed from the guide tube so that the first pair of arms resiliently move away from each other and are disposed on a common lateral side of the spinous processes.