A high‐precision, computer‐controlled monochromator of modest cost is described. The folded sine bar is used for the grating drive that provides high linearity even for large scanning angles. With a 200 steps/turn stepper motor and 600 grooves/mm grating, the minimum step size in first order is 0.05 nm, which can be further reduced. Over the 300–750 nm range, a bandpass better than 0.1 nm and a reproducibility of ±0.05 nm can be achieved. The stray light rejection of 8.9×10−7at 5.5 nm from the laser line is remarkable for this single grating instrument. Its performance promises to be an important tool for most forms of laser spectroscopy.