An expandable interbody fusion device for implantation into an intradiscal space between two opposing vertebral bodies of a spine, comprising: a first endplate having an outer surface configured to contact one of said vertebral bodies and an opening extending through said outer surface; a second endplate having an outer surface configured to contact the other vertebral body and an inner support surface, said second endplate having opposing spaced apart sidewalls (36,38) and opposing spaced apart front and rear endwalls defining therewithin a fully bounded interior cavity, said support surface being within said interior cavity, said first endplate being received within said interior cavity, said second endplate having at least one opening extending through said outer surface and said support surface and communicating with said interior cavity, said rear endwall defining therethrough a fully bounded channel in communication with said interior cavity, said first endplate being movable in an expansion direction relative to said second endplate toward the opposing vertebral body; a plurality of inserts, each having an upper surface, an opposite lower surface, a front end, a rear end 106 and an open rearward facing opening extending through said upper surface, said lower surface and the rearmost surface of said rear end, each insert being configured to be introduced one below the other between said first endplate and said second endplate through said channel into said interior cavity in an insertion direction that is substantially perpendicular to said expansion direction and supported by said support surface therewithin with the front end of each said insert adjacent the front endwall of said second endplate and the rear end of each said insert adjacent the rear endwall of said second endplate, said rearward facing opening of each insert communicating with said channel and being in at least partial alignment with said openings (32, 54) through said first endplate and said second endplate; and locking surfaces on each of said inserts to lock said inserts in said device. a first endplate having an outer surface configured to contact one of said vertebral bodies and an opening extending through said outer surface; a second endplate having an outer surface configured to contact the other vertebral body and an inner support surface, said second endplate having opposing spaced apart sidewalls (36,38) and opposing spaced apart front and rear endwalls defining therewithin a fully bounded interior cavity, said support surface being within said interior cavity, said first endplate being received within said interior cavity, said second endplate having at least one opening extending through said outer surface and said support surface and communicating with said interior cavity, said rear endwall defining therethrough a fully bounded channel in communication with said interior cavity, said first endplate being movable in an expansion direction relative to said second endplate toward the opposing vertebral body; a plurality of inserts, each having an upper surface, an opposite lower surface, a front end, a rear end 106 and an open rearward facing opening extending through said upper surface, said lower surface and the rearmost surface of said rear end, each insert being configured to be introduced one below the other between said first endplate and said second endplate through said channel into said interior cavity in an insertion direction that is substantially perpendicular to said expansion direction and supported by said support surface therewithin with the front end of each said insert adjacent the front endwall of said second endplate and the rear end of each said insert adjacent the rear endwall of said second endplate, said rearward facing opening of each insert communicating with said channel and being in at least partial alignment with said openings (32, 54) through said first endplate and said second endplate; and locking surfaces on each of said inserts to lock said inserts in said device.