Improved bone plate systems are described herein. In some instances, a bone plate system can include a base plate, at least one retainer plate, and at least one spacer. The at least one retainer plate is configured to reside on the base plate in a free floating manner and can receive at least one fastener to secure the retainer plate to the at least one spacer, thereby providing a plate system that attaches to a spacer. In other instances, a bone plate system can include a base plate having one or more push plates that can engage at least one spacer.