An expandable fusion device for implantation between two adjacent vertebrae, the device comprising: an actuator comprising a drive feature and a longitudinal axis ; a wedge assembly having a distal wedge and a proximal wedge and coupled to the actuator, the wedge assembly providing a width expansion of the device; a ramp assembly having a distal ramp and a proximal ramp and slidably coupled with the wedge assembly, the ramp assembly providing a height expansion of the device; an upper endplate assembly having a first endplate and a second endplate and slidably coupled with the ramp assembly; a lower endplate assembly having a third endplate and a fourth endplate and slidably coupled with the ramp assembly; a width comprising an external width of at least one of the upper endplate assembly and the lower endplate assembly ; and, a height comprising an external distance between the upper endplate assembly and the lower endplate assembly ; wherein, the device is configured such that actuation of the drive feature by a first number of actuations in a first actuation direction increases the width without increasing the height; actuation of the drive feature by a second number of actuations beyond the first number of actuations in the first actuation direction increases at least one of the height and the width; the distal wedge and the proximal wedge move toward one another and slide on the ramp assembly when actuating the drive feature ; resulting in a width expansion; and, only after the width expansion that occurs as the distal wedge and the proximal wedge move toward one another and slide on the ramp assembly , the distal ramp and the proximal ramp then start moving toward one another when actuating the drive feature , resulting in a delayed height expansion. an actuator comprising a drive feature and a longitudinal axis ; a wedge assembly having a distal wedge and a proximal wedge and coupled to the actuator, the wedge assembly providing a width expansion of the device; a ramp assembly having a distal ramp and a proximal ramp and slidably coupled with the wedge assembly, the ramp assembly providing a height expansion of the device; an upper endplate assembly having a first endplate and a second endplate and slidably coupled with the ramp assembly; a lower endplate assembly having a third endplate and a fourth endplate and slidably coupled with the ramp assembly; a width comprising an external width of at least one of the upper endplate assembly and the lower endplate assembly ; and, a height comprising an external distance between the upper endplate assembly and the lower endplate assembly ; wherein, the device is configured such that actuation of the drive feature by a first number of actuations in a first actuation direction increases the width without increasing the height; actuation of the drive feature by a second number of actuations beyond the first number of actuations in the first actuation direction increases at least one of the height and the width; the distal wedge and the proximal wedge move toward one another and slide on the ramp assembly when actuating the drive feature ; resulting in a width expansion; and, only after the width expansion that occurs as the distal wedge and the proximal wedge move toward one another and slide on the ramp assembly , the distal ramp and the proximal ramp then start moving toward one another when actuating the drive feature , resulting in a delayed height expansion. <EOS>