An expandable interbody spacer for the spine is provided. The spacer includes upper and lower endplates simultaneously movable with respect to a housing along an axis transverse to a longitudinal axis to increase or decrease the height of the spacer selectably along both an anterior side and a posterior side for uniform expansion/contraction of the endplates or only along the anterior side for angular expansion/contraction of the endplates. A spacer deployment instrument is provided that is selectable to effect uniform or angular expansion/contraction. When uniform expansion/contraction is selected a gear on an anterior rod is engaged with a gear on a posterior rod to simultaneously rotate both rods in opposite directions. Opposite threads on actuators of the spacer effect translation of the actuators in the same direction along the longitudinal axis.