Single-channel fluorescence detectors provide extremely low limits of detection for analytes separated by capillary electrophoresis (CE), but little structural or diagnostic information. In wavelength-resolved fluorescence detection, complete fluorescence emission spectra are acquired for every analyte separated by CE. The fluorescence spectral information has been used for DNA sequencing and to identify the tyrosine and tryptophan content of peptides. In addition, a variety of diagnostic uses for the fluorescence information exist, including monitoring excitation source stability and the pH, organic content and impurities in the running buffer. The popularity of spectrally resolved fluorescence detection in CE is expected to increase just as diode-array detection has become relatively common for ultraviolet-visible absorbance.