Various embodiments described herein provide devices and associated methods for treating spinal disease by implanting one or more interspinous process spacing devices. In one embodiment, an interspinous process spacing device includes a first attachment side, a second attachment side, a spacer tray, and a securing means. The spacer tray extends from the first attachment side and is slideably insertable through a spacer tray slot formed in the second attachment side. The spacer tray is adapted to be positioned between a spinous process of a first vertebra and a spinous process of an adjacent second vertebra, and the spacer tray includes a trough formed in a top surface of the spacer tray. The securing means is configured to engage the trough of the spacer tray to secure the second attachment side relative to the first attachment side.