System, including methods, apparatus, and kits, for bone fixation using a fixation device including a mounting portion and a fastener that attaches to the mounting portion. In some embodiments, the fixation device may include first and second mounting portions configured to be disposed across a bone from each other and secured with a fastener that extends from one of the mounting portions, through the bone, and to the other mounting portion. The system also may include a tool to facilitate installation of the fixation device.