The present disclosure relates to semiconductor structures and, more particularly, to electrostatic discharge (ESD) devices and methods of manufacture. The structure includes a bipolar transistor device, including a base region, having a base contact region, in a first well of a first conductivity type, a collector region, having a collector contact region, in a second well of a second conductivity type, and an emitter region, having an emitter contact region, in the first well, located between the base contact region and the second well, and a reverse-doped resistance well, of the second conductivity type, located in the first well of the first conductivity type between the base contact region and the emitter contact region structured to decrease turn-on voltage of the bipolar transistor device.