An expandable interbody fusion device configured for placement into the intradiscal space between vertebral bodies in a lumbar spine from a lateral approach. The device is expanded by the insertion of a plurality of wafers into the device in situ. The length of the device is configured to extend on the vertebral body endplate from pedicle to pedicle and to reside interiorly of the ring apophysis with at least a portion of the device resting on the area of increased bone density at the posterior portion of the endplate between the pedicles.