Methods for matching semiconductor plasma processing chambers using a calibrated spectrometer are disclosed. In one embodiment, plasma attributes are measured for a process in a reference chamber and a process in a sample chamber. Measuring the plasma attributes during process perturbations allows for the correlation of process parameters to the plasma optical emission spectra. The process parameters can then be adjusted to yield a processed substrate which matches that of the reference chamber. Methods for monitoring the stability of a plasma processing chamber using a calibrated spectrometer are also disclosed.