© 2015, Springer-Verlag Berlin Heidelberg. We generate 555.8-nm light with sub-MHz linewidth through the use of laser injection locking of a semiconductor diode at 1,111.6 nm, followed by frequency doubling in a resonant cavity. The integrity of the injection lock is investigated by studying an offset beat signal between slave and master lasers, by performing spectroscopy on the (6s)21S0--(6s6p)3P1 transition in magneto-optically trapped ytterbium, and by demonstrating additional laser cooling of 171Yb with the 555.8-nm light in a dual-wavelength magneto-optical trap (MOT). For the 1S0-3P1 spectroscopy, we confirm the linear dependence between ground-state linewidth and the intensity of an off-resonant laser, namely that used to cool Yb atoms in a 1S01P1 magneto-optical trap. A temperature of 60 μK is produced for 171Yb in the dual-wavelength MOT. Our results demonstrate the suitability of injection-locked 1,100–1,130-nm laser diodes as a source for sub-MHz linewidth radiation in the yellow–green spectrum.