The photophysics and spectroscopy of tryptophylglycine, tryptophylalanine, glycyltryptophan, alanyltryptophan, glycyltryptophylglycine, and tryptophan itself have been investigated by using steady-state and subnanosecond spectroscopy. For tryptophan and the peptides where the tryptophyl residue is N-terminal we demonstrate the involvement of the state of protonation on both the excited-state dynamics and the absorption and emission spectra. We show that the deprotonated amino group gives rise to red-shifted absorption and emission spectra and to a longer fluorescence decay time compared with the protonated form. pKa values over a range of temperatures were determined for tryptophan (23°C, 9.50), tryptophylglycine (23°C, 7.84), and tryptophylalanine (23°C, 7.79). The temperature dependence of the amplitude of the long-decay component in tryptophylglycine is attributable to the temperature dependence of the ground-state pKa. Examination of the Arrhenius plots for tryptophan, tryptophylglycine, and glycyltryptophan clarifies the role of the protonated amino group in fluorescence quenching. We suggest that the role of the protonated amino group in the fluorescence quenching of the N-terminal tryptophyl compounds is not proton transfer to the indole ring but an enhancement of charge transfer from the indole ring to the adjacent carbonyl group.