An expandable interspinous process fixation system (10,10') comprising: - a first endplate (20,20') for an intervertebral implant, wherein the first endplate comprises a first plate portion having a first upper surface and a first lower surface, wherein the first endplate further comprises first front ramped portions (31, 35, 51, 55) extending away from the first lower surface and first rear ramped portions extending away from first lower surface, the first endplate having a first lateral adjustment arm extending from a first edge thereof; - a second endplate (40,40') for an intervertebral implant, wherein the second endplate comprises a second plate portion having a second upper surface and a second lower surface, wherein the second endplate further comprises second front ramped portions extending away from the second lower surface and second rear ramped portions extending away from second lower surface, the second endplate having a second lateral adjustment arm extending from a first edge thereof; - a first fixed plate extending along a second edge of the first endplate opposite the first edge thereof, the first fixed plate extending substantially perpendicular to the first endplate and having an inner surface defining a first spinous process engaging surface; - a second fixed plate extending along a second edge of the second endplate opposite the first edge thereof, the second fixed plate extending substantially perpendicular to the second endplate and having an inner surface defining a second spinous process engaging surface; - a first sliding plate adjustably mounted on the first lateral adjustment arm such that the first sliding plate extends substantially perpendicular to the first endplate and has an inner surface defining a third spinous process engaging surface; - a second sliding plate adjustably mounted on the second lateral adjustment arm such that the second sliding plate extends substantially perpendicular to the second endplate and has an inner surface defining a fourth spinous process engaging surface; - a central ramp (110,110') positioned between the first endplate and the second endplate, wherein the body comprises rear endplate engaging ramps (116, 117) and - a driving ramp (130,130') positioned between the first endplate and the second endplate, wherein the driving ramp comprises front endplate engaging ramps (136,137); - wherein the apparatus is configured such that movement of the central ramp and the driving ramp toward one another causes the first and second endplates to move apart. - a first endplate (20,20') for an intervertebral implant, wherein the first endplate comprises a first plate portion having a first upper surface and a first lower surface, wherein the first endplate further comprises first front ramped portions (31, 35, 51, 55) extending away from the first lower surface and first rear ramped portions extending away from first lower surface, the first endplate having a first lateral adjustment arm extending from a first edge thereof; - a second endplate (40,40') for an intervertebral implant, wherein the second endplate comprises a second plate portion having a second upper surface and a second lower surface, wherein the second endplate further comprises second front ramped portions extending away from the second lower surface and second rear ramped portions extending away from second lower surface, the second endplate having a second lateral adjustment arm extending from a first edge thereof; - a first fixed plate extending along a second edge of the first endplate opposite the first edge thereof, the first fixed plate extending substantially perpendicular to the first endplate and having an inner surface defining a first spinous process engaging surface; - a second fixed plate extending along a second edge of the second endplate opposite the first edge thereof, the second fixed plate extending substantially perpendicular to the second endplate and having an inner surface defining a second spinous process engaging surface; - a first sliding plate adjustably mounted on the first lateral adjustment arm such that the first sliding plate extends substantially perpendicular to the first endplate and has an inner surface defining a third spinous process engaging surface; - a second sliding plate adjustably mounted on the second lateral adjustment arm such that the second sliding plate extends substantially perpendicular to the second endplate and has an inner surface defining a fourth spinous process engaging surface; - a central ramp (110,110') positioned between the first endplate and the second endplate, wherein the body comprises rear endplate engaging ramps (116, 117) and - a driving ramp (130,130') positioned between the first endplate and the second endplate, wherein the driving ramp comprises front endplate engaging ramps (136,137); - wherein the apparatus is configured such that movement of the central ramp and the driving ramp toward one another causes the first and second endplates to move apart.