Abstract: An adjustable threshold assembly of simple construction and inexpensive to manufacture includes a bar member vertically adjustable in a channelway of a base member. A plurality of threshold height adjusting screws extend vertically downward through openings in a transverse bridge wall of the bar member and between and in self-tapped screw thread-like engagement with a pair of longitudinally extending opposed vertical walls of the bridge wall. The facing vertical sides of the opposed walls are advantageously formed with longitudinally extending extruded serrations of a cross-sectional shape approximately matching the cross-sectional shape of the screw threads of the adjusting screws to facilitate self-tapping of the adjusting screws into the opposed walls of the bar member.